-26 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



The uiiitli abdomiual segment is unusually well developed in the Attaiidie and the Cerato- 

 campidie, sonietiiiics, as has been pievionsly stated, hearing a true "caudal horn," which takes 

 the place of that usually growin<'' on the eighth segment. In the KhopalDcera, the suranal plate 

 is iu general, esi)ecially in Hesperida^ and Papilionid.i', .small and rounded, much as in the 

 Noctuida', hut in the Xym])halida' it is more or less S|)('cialized, and remarkably so in the larva of 

 Xco)i;i»ipha phodou and other satyrines, where it is greatly elongated and forked. (iSee figures 

 in Scudder's "Butterflies of New England;'' also W. Midler's figures of larva of Prepoua.) 



The paranaJ lobrs. — These are the hoinologues of the two anal valves {ndnila' of Burnieister, 

 "the podical plates" of Huxley) observed in the cockroaeli, and occurring in nearly all, if not all, 

 insects. In Geometrid larvie they are full, fleshy, lobe like, or i)apilliform, bounding the areas on 

 each side, and appear as if i)rojecting backward from the base of the anal legs. 



In the Ceratocampida' these paranal lobes are not well developed. In the larva of Cerura they 

 are much as iu Geometrid caterpillars, where they end each in a seta. 



The paranal forks. — We have already called attention to these two bristles iu our description 

 of the larva' of Cerura. (Proceedings Boston Soc. N. H. xxiv, p. 55;3.) They are well developed, 

 arising from the cud of a papilla projecting directly backward. Their use has been indicated by 

 Mr. ,Tohn Uellins,' who refers to a pair of sharp points underneath the anal flap, " which are used to 

 throw the pellets of frass to a distance." Occurring in Notodontian and other arboreal caterpillars, 

 notably the tree-inhabiting Geometrids, they are wanting in Noctuida- (including Acronycta and 

 Catocala), Sphingida*, and Ehopalocera, as well as the lower Geometrids and the Microlepidoptera, 

 and are not developed in the Si)hingidie. In Ichthyura (Clostera) they are slightly developed. In 

 the European Urnptcnjx sainbucata (received from M. P. Chretien) these lobes are very large, 

 papilliform, and setiferous, and in our Chcerodes, etc., they are similarly developed and the 

 use of the two setre or the fork is undoubtedly the same as in Cerura. 



Till' infraanal lobe. — My attention was first called to this lobe or flap while examining some 

 Geometrid larvae It is a thick, conical, fleshy lobe or llap, ending often in a hard cliitinous point, 

 and situated directly beneath the vent. In appearance it is somewliat like the eggguide of the 

 Acrydii, though the latter is thin and flat. Its use is evidently to aid in tossing the ])ellets of 

 excrement away so as not to allow them to come in contact with the body. In a large not iden- 

 tified Geometrid worm, which lives on the ash, this Hap is large and conical, ending in a blunt 

 chitinous point. In a large geoaieter bt-longiug to another genus, the tip is sharper and harder, 

 and in what is probably a larva of Endropia, while the ])aranal forks are well develojjed, the 

 infraanal lobe ends in a stiff bristle. Whether this infraanal lobe is the homologue of the ninth 

 nrosternite or ventral plate I will not at present undertake to say. 



Glanihilar .sefrc— Among the Notodontidie the freshly hatched larvae of several genera are 

 provided with glandular hairs of various shapes. In iJittdna iiitegerrima they are clavate; in 

 Diisiihplna anrjuiiia they are clavate, somewhat flattened, and are dark, but clear at the tii),^ while 

 in all the other caterpillars we have observed that the glandular hairs are confined to the body, 

 those on the head tapering to a point, and ai)parently not fitted for secreting a fluid; those on the 

 head of Dasylophia are glandular, all ending in a slight transparent bulb. 



Other genera of this grouj) will iirobably on further investigation be found to possess glandular 



:seta' in their first larval stages. They occur in tlie freshly hatched larva of what is probably a 



■sjiecies of Heterocampa, also in Xadata f/ibbos(t, Ichthyura iiivhtsa, and Plicositi riiiiosa. 



■ It is to be observed that the freshly hatched caterpillars of Ceratonia tricolor Smith are 



provided with glandular hairs. They are tlatteued at the tip, which is slightly tridentate, with 



'Tlio use of thcho I finil expluiiicil by Mr. Hcllins in liis dcscrijition of tlie larva of C. hijida in liiirklL^r's Liirv:i> 

 of liritisli liiittertlics and Motlis, ii, p. 112, as follows: "At the tip of tli(! anal flap are twosliarp points, and ai\otlior 

 pair uiidenioath, wliii-h -.nv, used to throw tlio pellots of frass to a distauco." Similar dun^'forka are very generally 

 present in (Jeonietrid larva-, the paraual papilliform tubercles bciun well developed, thouyli wo have not seen them 

 lu use. 



1 have noticed a caterpillar of ('. horralis iu the process of dofecatiur;, and with the forceps pulled olV a jxdlct 

 which was held by the two spines of the paranal tubercles. Mr. Dyar tells me he has both seen and heard the 

 caterpillars casting their pellets with the ai<l of their spine against the side of a tumbler. 



■ ^I'l.XXXVII, lig 11. <ilandular hairs of Dasylophia; «, of body; b, of the head ; c, of inothor.icic shield. 



