Packard.] 
106 
[May 7, 
describing Geometric caterpillars. It varies much in shape and or- 
namentation in Notodontidye, also in Attacidye and Ceratocampidye. 
In Noctuidae it is not, so far as we know, very characteristic. It 
seems to be especially developed in those larvae which constantly 
use the anal legs for grasping, while the front part of the body is 
more or less raised. It is thus correlated with enlarged anal legs. 
Morphologically this plate appears to represent the dorsal arch 
of the tenth or last abdominal segment of the body , 1 and is the 
“anal operculum,” or lamina supraanalis of different authors . 2 
This suranal plate is in the Plat} T ptericidye remarkably elongated, 
forming an approach to a flagellum-like terrifying appendage, and 
in the larva of Aglia tau forms a long prominent sharp spine. Its 
shape also in Cerura caterpillars is rather unusual, being long and 
narrow. In the Ceratocampidye, especially in Anisota, Dryocampa, 
Eacles and Citheronia, this plate is very large, the surface and 
edges being rough, tuberculated, while it seems to attain its maxi- 
mum in Sphingicampa, being triangular, ending in a bifid point. 
The ninth abdominal segment is unusually well developed in the 
Attacidye including the Ceratocampidse ; sometimes, as has been pre- 
viously stated, bearing a true “caudal horn,” which takes the place 
of that usually growing on the eighth segment. In the Rhopalo- 
cera the suranal plate is in general, especially in Hesperidye, Papil- 
ionidse, small and rounded, much as in the Noctuidse ; but in the 
Nymplialidse it is more or less specialized, and remarkably so in 
the larva of Neonympha phocion and other Satyrines, where it is 
greatly elongated and forked. (See figures in Scudder’s “-Butterflies 
of New England,” also W. Muller’s figures of larva of Prepona.) 
The paranal lobes. — These are the homologues of the two anal 
valves (valvulce of Burmeister, “the podical plates” of Huxley) ob- 
served in the cockroach, and occurring in nearly all, if not all, in- 
sects. In Geometrid larvye they are full, fleshy, lobe-like or papilli- 
form, bounding the areas on each side, and appear as if projecting 
backward from the base of the anal legs. 
In the Ceratocampidye these paranal lobes are not well developed. 
In the larva of Cerura they are much as in Geometrid caterpillars, 
where they end each in a seta. 
1 See my note : “The number of abdominal segments in Lepidopterous larvae.” Amer- 
ican Naturalist, March, 1885, pp. 307, 308. 
2 Compare E. Haase, “On the constitution of the body in the Blattidae.” Ann. and 
Mag. Nat. Hist., March, 1890, 227-234. Translated from Sitzungsb. Ges. Naturf. 
Freunde zu Berlin, Jahrg., 1889, 128-136. 
