MYRIAPODA. 353 



corresponds to the ligula of the Crustacea; next come two pairs of 

 little feet, the second of which, in several, resemble large hooks, 

 that appear to replace the four jaws of the last mentioned animals, 

 or the two jaws as well as the lower lip of Insects: they are a sort 

 of buccal feet. The antennas, two in number, are short, somewhat 

 thicker towards the extremity, or nearly filiform and composed of 

 seven joints in some; in others they are numerous and setaceous. 

 Their visual organs are usually composed of a union of ocelli, and 

 if in others they present a cornea with facets, the lenses are still 

 larger, rounded, and more distinct, in proportion, than those of the 

 eyes of Insects. The stigmata are frequently very small, and their 

 number, owing to that of the annuli, is usually greater than in the 

 latter, where it never exceeds eighteen or twenty. The number of 

 these annuli and that of the feet increase with age, a character 

 which also distinguishes the Myriapoda from Insects, the latter ab 

 ovo always having the number of segments peculiar to them, and all 

 their legs with hooks, or true legs, being developed at once, either 

 at the same epoch or when they pass into their pupa state. The 

 Myriapoda live and increase in size longer than other Insects. 



From this ensemble of facts, we may conclude, that these animals 

 approach the Crustacea and Arachnides on the one hand, and the 

 Insects on the other; but that as respects the presence, form and di- 

 rection of the branchiae, they belong to the latter. 



We divide them into two families, perfectly distinct both in their 

 organization and habits, and forming two genera according to the 

 system of Linnasus. 



FAMILY I. 



CHILOGNATHA. 



The body generally crustaceous and frequently cylindrical; the 

 antennas somewhat thicker near the end or nearly equal, and com- 

 posed of seven joints; the two thick mandibles without palpi, very 

 distinctly divided into two portions by a median articulation with in> 

 bricated teeth, implanted in a cavity of its superior extremity; a 

 species of lip ligula situated immediately above, that covers them* 

 is crustaceous, plane, and divided on its exterior surface by longitu- 

 2 U 



