Part 4 — Chapter V. Microscopic Fauna.

BY THOMAS BOLTON, F.R.M.S.

The writer in drawing up the following summary of the local Microscopic Fauna, knowing how limited a space is allowed, has in several of the families given only the more rare and remarkable species which have come under his own observation. The organisms included in this division are abundant all round Birmingham; in the canals, reservoirs, and rivers, in the swags and catchpits, amongst the spoil heaps of the “Black Country,” and in the numerous clay-pits on the farm lands.

INSECTA.

It is desirable to call attention to the identification of the larvæ of the Trichopterous insects Agraylea multipunctata and Oxyethira costalis, by Messrs. Kenneth J. Morton and Robert McLachlan. The perfect insects were bred from larvæ collected in this district, as referred to in the “Entomologists’ Monthly Magazine,” May and June, 1886. So many problems in the life history of insects, having aquatic larvæ, remain unsolved, that it is desirable that microscopists should pay more attention to this subject.

ARACHNIDA.

The curious Diving-bell Spider, Argyroneta aquatica, is found in the pools at Sutton Park; and a great variety of species of the Water-Mites is generally distributed. Mr W. Saville Kent reports that several specimens received from this district are new to science.

Tardigrada, viz., Macrobiotus Hufelandii, and other species, may be found almost everywhere, if carefully looked for amongst damp moss and decaying algæ.

CRUSTACEA.

In this class should be mentioned the freshwater Crayfish, Astacus fluviatilis, not of course a microscopic organism; but if it were omitted here it would not appear in any of the other reports. This species is fairly distributed in most of the smaller brooks, in the canals, and larger reservoirs, but is not so abundant or so large as it is on the lime formations round Oxford. Two other large microscopic species of this class, the freshwater Shrimp, Gammarus pulex, and the water Wood-louse, Asellus vulgaris, are always present, the former busy in its office of scavenger in the sandy bottoms of the brooks and ditches, and the latter climbing about, like a monkey, amongst the water weeds, investigating the mass of living and decaying organisms with which the weeds are clothed.

Entomostraca.

The members of this sub-class are also to be found everywhere, but it is desirable to call special attention to the discovery for the first time in Great Britain of the wonderfully transparent Leptodora hyalina, at a visit of the Birmingham Natural History and Microscopical Society in 1879, to the Olton Reservoir, near Solihull. It has since been found in many localities, and is very abundant in the summer and autumn in the Warwick Canal and several reservoirs. Hyalodaphnia Kahlbergensis is very generally found with it. Argulus coregoni is found in the Birmingham and Warwick Canal. It had only been discovered in Great Britain previously in the tanks of the Royal Aquarium at Westminster, which, of course, are not used for British fish exclusively. The Fairy-shrimp, Chirocephalus diaphanus, is found in only one locality in the district, near Knowle. A few specimens of the very rare Lynceus acanthocercoides were found near Bewdley, and amongst other local finds may be mentioned Moina rectirostris, Macrothrix roseus, and Ilyocryptus sordidus.

POLYZOA.

These are generally distributed; Alcyonella fungosa, Plumatella repens, Fredericella sultana, and Paludicella Ehrenbergii cover the root-fibres under the banks of the River Avon, at Evesham. Lophopus crystallinus is occasionally found in the brooks to the south west of Birmingham. Cristatella mucedo is often very abundant in the larger reservoirs at Sutton Park, Barnt Green, Olton, &c. Fredericella and Paludicella, have several times been seen in the town water supplied by the Corporation.

ROTIFERA.

The district appears to be very rich in these organisms, and a good number of new species from this locality are enumerated in the admirable Monograph on this family now being published by Dr. C. T. Hudson and Mr. P. H. Gosse. In the five parts already published (July 12th, 1886), they record one hundred and ninety-two species, of which ninety-eight have been found in this district, twenty-two being new species. Of the fifteen Flosculariæ eight species have been found here, viz., Flosculariæ regalis (new), F. coronetta, F. ornata, F. cornuta, F. campanulata, F. ambigua, F. calva, and F. mutabilis (new). Stephanoceros Eichhornii may sometimes be seen quite clothing the water weeds in the canals and pools. The always attractive building Wheel-animalcule, Melicerta ringens, is occasionally present in abundance in the canals, rivers, and pools all over the district. The writer has taken Melicerta conifera several times. Melicerta tubicolaria was found by Dr. Hudson in Sutton Park, and has since been found in other localities in this district. Limnias ceratophylli is very generally abundant. Limnias annulatus has been found in two places. Œcistes cystallinus is common, and Œ. intermedius not uncommon. Although beyond the radius, it may be interesting to note that Melicerta Janus, new to England, was taken in one of the Shropshire meres, by the writer on the 23rd of June, 1886. It had only been found in Scotland before, by Mr. Hood, in 1880. The new rotifer, Œcistes umbella, was found by Mr. A. W. Wills, together with the rare Œ. pilula in a pool at Sutton Park. The charming clustered rotifer, Lacinularia socialis, only appears in the hot summer months, but was surprisingly abundant last year in the River Avon at Warwick, literally clothing the weeds with life. This rotifer was in fair abundance a few years back in the Barnt Green Reservoir, and last year in the neighbouring canal. The still more charming free-swimming clustered rotifer, Conochilus volvox, is more generally present, but is not always easy to detect, on account of its transparency and continuous quick movements. The writer has taken this rotifer in the pools at Sutton Park with a muslin net in such abundance as to form quite a jelly at the bottom of the net. He also found a new species, Conochilus dossuarius, in 1884. Of the Philodinidæ, the following have been found—Philodina roseola, P. citrina, P. megalotrocha, P. aculeata; Rotifer vulgaris, R. tardus, R. macroceros, R. macrurus; Actinurus Neptunius, Callidina elegans, and Adineta vaga. The rare and pretty little Microdon clavus may be found swimming about in Coleshill pool. Asplanchna, Synchæta, Polyarthra, and Triarthra, may be netted in enormous numbers in the summer months, especially in all the canals and larger pools, and they occasionally abound in the smaller pools and even in ditches, together with a great variety of the creeping ones, such as Philodina, Rotifer, Notommata, Brachionus, Anuræa, &c. The wonderful variety of these living together in a small ditch in Sutton Park is reported upon in a short paper read by the writer before the Birmingham Natural History and Microscopical Society in February last, and published in the “Midland Naturalist,” July, 1886. Hydatina senta and Rhinops vitrea may be looked for amongst the Euglena viridis often seen luxuriating in farm yard drainage. The abnormal species, Pedalion mira, was found at Knowle in 1884, in fair abundance. The spiny Anuræa longispina was found at Olton Reservoir very soon after it was first discovered in America, and it soon afterwards abounded in the town water, and may be found in most large reservoirs.

ANNELIDA, ETC.

Some interesting examples of the Oligochæta have been found in this locality, most of which have been identified by Professor E. Ray Lankester or Mr. E. C. Bousfield, and of these the following are noteworthy—Chætogaster limnæi, and C. diaphanus, Nais hamata, N. lurida, N. appendiculata, and N. barbata; Stylaria parasitica, Dero digitata, D. obtusa, D. Perrieri, D. limosa, and D. crassa; Salvina serpentina, and Ælosoma quaternarium. The Cercaria (the larva of a fluke) which infests the common Water Snail, Limnæa stagnatis, is occasionally found; also Mesostomum rostratum, Derostomum vorax, Planaria lactea, and Piscicola geometrica.

HYDROZOA.

Both Hydra vulgaris and H. viridis are of course found everywhere. Cordylophora lacustris, which is usually more abundant in brackish water, was found last year in the canal at Hamstead, near Handsworth. The writer has found it in the Stourbridge canal, and in the River Stour. Some years back the writer heard of a canal boat being docked at Dudley Port which was found to be clothed with this Hydrozoon as with velvet.

SPONGIDA.

The freshwater sponges, Spongilla fluviatilis and S. lacustris, are abundant, but no one has taken up the subject in this district, to work out the different species into which this genus is now divided.

INFUSORIA.

When Mr. W. Saville Kent was preparing his manual on this subject, he was supplied with a great variety of specimens from this district, many of which proved to be new ones. The following are worthy of mention: Anthophysa vegetans, Rhipidodendron Huxleyi, Spongomonas intestinalis; various Codosigæ and other Choano-flagellate monads, including Salpingœca Boltoni, Kent, (new); Euglena acus; Dinobryon sertularia; Synura uvella; Uroglena volvox (very general); Distigma proteus; Hemidinium nasutum; Peridinium tabulatum; Ceratium longicorne; Nassula ornata; Trachelius ovum; Spirostomum teres, and S. ambiguum; Stentor polymorphus, S. Barretti, S. cœruleus, and S. niger; Folliculina Boltoni, Kent (new.) The writer has found several free swimming Tintinnus, not corresponding with any that Mr. W. Saville Kent enumerates; Didinium nasutum; Trichodina pediculus; Scyphidium Fromentellii; Spirochona gemmipara; Vorticella chlorostigma, and V. monilata; Carchesium polypinum, and C. epistylidis; Zoothamnium arbuscula; Vaginicola tincta; Thuricola folliculata; Cothurnia imberbis; Ophrydium versatile, O. Eichhornii, and O. sessile; Stichotricha remex; Atineta lemnarum, A. grandis, and A. mystacina; Dendrosoma radians.

RHIZOPODA.

The following have been found: Amœba proteus, A. verrucosa, A. radiosa, and A. villosa; Ouramœba vorax; Lithamœba vorax, Lankester (new); Difflugia pyriformis, D. spiralis, and D. corona; Cyphoderia umbella; Arcella vulgaris; Actinophrys sol; Raphidiophrys pallida, and R. elegans; Actinosphærium Eichhornii; Acanthocystis chætophora; Archerina Boltoni, Lankester (new); Clathrulina elegans, and Biomyxa vagans.