Note 8 — LETTER XXVIII.

There is no general rule without exceptions, and no character is so universal as to be distinctly exhibited by every member of a class or other natural group. Thus, in the majority of the mites (Acarus L.) the body is marked by no segments, and the only articulation or incision is in the legs, palpi, &c. But as the exception does not make void the rule, so neither does the extenuation or absence of some primary character at its points of junction with others, in some individuals, annihilate the class or group.