MEMOmS OF THE NATIONAL ACADEMY OF SCIENCES. 25- 



and the spine-like tenant hair, there is a lamellate, flattened hair. PI. XXXVII, flg. 10, represents 

 the end of a thoracic leg of Hefenwamptt mautco. Besides the nnguis and tenant hair at the end, 

 there are two singular, thin, flattened, oval leaf-like seta' arising near the middle of the joint. 

 The use of the claw and teinint hair as grappling organs is quite apparent, but the function of the 

 singular lamellate hairs is a matter of conjecture. 



Iliuts oil the origin of the prothoracio or cereical nhield. — Xot only in the wood-boring Lepi- 

 doptera, such as the larva- of the Hepialida^, and the Cossidie, as well as the Sesiidse, is there a 

 well marked cervical shield, but also in the grubs of Cerambycida", and some other Coleopterous 

 families whose larva? bore in hard substances, and in such groups this hard, chitinous plate 

 serves to protect the base of the head and adjacent parts of the body most exposed to injury. 

 Developed in the borers of widely diilerent orders, aiul obviously of direct use to the animal, it 

 has probably arisen in response to an external stimulus, an extra quantity of chitin having been 

 developed by the hypodermal cells of the tergal arch of the i)rothoracic segment, which by friction 

 has become thickened, just as the skin of the sole of the foot in savages becomes thick and horny 

 in those accustomed to go barefoot in dry, rough places. 



In the lower lepidopterous families, as tlie Tineina, Tortrieida', ryralida\ as well as in the 

 low-feeding Noctuida', which hide under stones, such as the cutworms, a well developed cervical 

 shield is generally present. 



In the Bbmbyces, which feed exposed both on trees and on herbaceous plants, the cervical 

 shield is rarely even well developed, but there are sporadic cases of its development, and especially 

 of its appearance in the early stages and of its suppression in later larval life, which are of interest 

 and merit notice. 



In the Xotodoutian genus Cernra, the prothoracic segment is unusually broad and flat above, 

 although it is not smooth, chitinous, or polished ; whether its use is to support the large lateral 

 tubercles or to resist pressure and friction is a question. 



In the first stage of Dasijiophia anfjuina there is a small cervical shield (PI. XXXVII, flg. lie), 

 which bears four glandular sette on each side of the median red dorsal line. 



In Dntaiia iiitef/errima, a small, transversely oblong, conspicuous black cervical shield is 

 present in the freshly hatched larva and in the subsequent stages. There is, however, no shield 

 or rudiments of one in Edema albifrons or in Heterocampa and Macrurocampa. 



In the other Bombyces there is no genuine shield, but in the first stage of some forms the two 

 dorsal piliferous warts on the prothoracic segment are more or less enlarged and sometimes 

 coalesced so as to indicate that the shield may have been formed by the enlargement and 

 coalescence of these warts. 



The siipraanal or suranal plate.— This i^\a.te, the pode.v of Kirby and Spence, in Bombycine 

 and Geometrid larvic, both as to its shape and ornamentation, attbrds excellent characters for 

 distinguishing species, and we have found it of great use, especially in describing Geometrid 

 caterpillars. It varies much in shape and ornamentation in Xotodontidiip, also in Attacidse .and 

 Ceratocampid;¥. In Noctuida^ it is not, so far as we know, very characteristic. It seems to be 

 especially developed in those larva^. 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,' and is the "anal operculum" or lamina siipraaiialin of diff'erent authors.^ 

 This suranal plate is in the Platyptericid* remarkably elongated, forming an approach to a 

 flagellum-like terrifying ap])endage, and in the larva of AfjUa tun, forms a long, prominent siiarp 

 spine. Its shape also in Cernra caterpillars is rather unusual, being long and narrow. In the 

 Ceratocampidaj, especially in Anisota, Dryocampa, Eacles, and Citheronia, this plate is very 

 large, the surface and edges being rough and tuberculated, while it seems to attain its maximum 

 in Sphingicampa, being triangular, ending in a bifid point. 



' See my note, "The number of abdominal segments in Lepidopterous larv.-e." American Naturalist, March, 

 1885, pp. 307, 308. 



- Compare E. Haase, " On the constitution of the body in the Blattid:i"." Ann. and Ma;j;-. Nat. Hist., March, 1890,. 

 227-234. Translated from Sitznngsb. Ges. Naturf. Frenude zu Berlin, .lahrg., 1889, 128-136. 



