MEMOIRS OF TUE NATIONAL ACADEMY OF SCIENCES. 25 



and the spine-like tenant hair, there is a liiiiiellate, tiattened hair. PI. XXXVII, fi^-. 10, represents 

 tlie end of a thoraeie leg "f UctcroctniipK vuoitco. Besides the ungnis and tenant hair at tlie end, 

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

 The use of the elaw and tenant hair as grappling organs is (piite ai)parent, but the function of the 

 singular lamellate hairs is a matter of eonjeeture. 



Hints on the origin of the prothonicic or cervical shield.— "Sot only in the -wood-boring Lepi- 

 dojitera, such as the larva' of the IIei)ialida', aiul the Cossida', as well as the Sesiid;!?, is there a 

 well r.iarked cervical shield, but also in the grubs of Cerambyciche, and some other Coleopterous 

 families whose larv;e bene in hard substances, and in such groups this hard, chitiuous plate 

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

 Develoi^ed in the borers of widely different orders, and obviously of direct use to the animal, it 

 has probably arisen in response to an external stimulus, an extra (piantity of chitiu having been 

 developed by the hypodermal cells of the tergal arch of the prothoraeic segment, winch by friction 

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

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



In the lower lepidopterous families, as the Tineina, Tortricida', Pyralid:e, as well as iu the 

 low-feeding Noctuidiie, which hide uuder stones, such as the cutworms, a well developed cervical 

 shield is generally present. 



In the Bombyces, 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 Notodontian genus Cerura, the prothoraeic 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 flrst stage oi IMsijlophia anyuina there is a small cervical shield (PI. XXXVII, flg. lie), 

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



In Datana integcrrima, a small, transversely oblong, conspicuous black cervical shield is 

 present iu 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 prothoraeic segment are more or less eidarged and sometimes, 

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

 coalescence of these warts. 



The supraanal or suranal ^>/a/c.— This plate, the j>o(/e./- of Kirby and Spence, in Bombycine- 

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

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

 caterpillars. It varies much in shape and ornamentation in ISTotodoutidiT, also iu Attacid* .and 

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

 especially developed iu those larviB 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 snpraan((Iis of diflerent authors.^ 

 This suranal ]date is in the PlatyptericidcB remarkably elongated, forming an approach to a 

 flagellum-like terrifying appendage, and in the larva of Aglia tun forms a long, prominent suarp 

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

 Ceratocampidie, especially iu Auisota, 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 abdomiuiil segments in Lepidopterous larvie."' .American Naturalist, March, 

 1885, pp. 307, 3(18. 



= Compare E. Haase, " Ou the constitution of the body iu the Blattiihe." Ann. and Mag. Xat. Hist., March, 1890,. 

 227-234. Translated from Sitzuugsb. Ges. Naturf. Freuude zu Berlin, Jahig., 1889, 128-136. 



