MEMOIKS (W TIIK NATIONAL ACWDEAIY OF SCIKNCES. 



97 



(I'l. LX, figs. 2, 2a, Sh, etc.). Penis c(mi))lic:ito(l; coiisistinj^ of tlio .slondiu- stvlo-likc penis proper, 

 forked at the end. and a wider broad triantr'ilnr aecessory or guard-plate (PI. XL, tig. 3*', 7") 

 situated above it. In the four North Auierieau species there seems t)nt little diH'erenc^e in the 

 dirt'erent parts of the genital armature, and these ean be best brought out by refei'eiice to my 

 eaniera drawings in Plates LIX. XLI. 



£^!/ff. — Elliptieal, flattened, each end alike, a little longer than l)road; shell very thin, parch- 

 ment-like, the surface with obscurely marked microscopic irregular he.xagoruil areas. The eggs 

 are laid in large patches on leaves. 



Larva. — Body cylindrical, slightly flattened at tiie end; armature consisting of two recurved 

 slender smooth mesothoraeic horns; prothoraeic spines reduced to low tubercles; all the other 



Fi^. 12- IHslributirm of the genus Anisota, 



dorsal and lateral spines of the body small, conical, acute; the two dorsal spines of the eighth 

 abdominal segment separate, remote, not fused into a median or caudal horn, but the two tubercles 

 i i on the ninth segment fu.sed into a caudal horn. Suranal plate rugose or granulated, with 

 from three to four lateral and two terminal stout conical spines. Body with conspicuous longi- 

 tudinal Ijands or stripes. 



Young larva, stage I. — Body not spiny with the exception of a pair of smooth horns a little 

 longer than the body is thick, slightly divided at the end, each division bearing a long seta. The 

 other spines represented by minute setiferous tubercles; tubercles I I being present. Suranal 



