246 INSECTA. 



with facets, the lenses are still larger, rounder, 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 increases with age, a charac- 

 ter 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 de- 

 veloped at once, either at the same epoch or when they pass 

 into their pupa state. M. Savi, professor of mineralogy at 

 Pisa, who has paid particular attention to the Iuli, has ob- 

 served, that on leaving the egg they are destitute of these 

 organs : they experience then a true metamorphosis. In 

 some, the male organs of generation are placed immediately 

 after the seventh pair of feet, on the sixth or seventh segment 

 of the body, and those of the female near the origin of the 

 second feet : in the others the two sorts of organs are situated, 

 as usual, at the posterior extremity of the body. The posi- 

 tion of the male organs of the first compared with that in 

 which they are placed in the Crustacea and Arachnides, 

 would seem to indicate the separation of the trunk and abdo- 

 men : with respect to those in which these organs are poste- 

 rior, we observe that an inversion of the successive order of 

 the stigmata takes place in an analogous portion of the body 

 of certain species, which appears to announce a similar dis- 

 tinction. 



The Myriapoda live and increase in size longer than other 

 Insects, and, according to Savi, two years are required to ren- 

 der the genital organs of some (the Iuli) of them apparent. 



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 direction of the braehesB, they belong to 

 the latter. 



We divide them into two families, perfectly distinct both 



