54 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



iiiid -lordaii, the Chalcosiidw. While the statement is made that all the Lepidoptera below the 

 more primitive butterflies possess this appendage, the above-named families excepted, it will be 

 interesting to ascei-tain whether there maj' not be here and there cases of its absence in scattered 

 genera, and perhaps subfamilies, of the moths. 



Kathariuer" has recentl_y published an excellent article, for the first time describing the 

 structure and flne anatomy of this appendage in Achrronfta afropoa, Deilephila elpeiwr. and two 

 species of Sphinx {S. con vol rid/, and S. Jigustri). 



While, as he says, there is no convincing proof of its being a scent structure, Kathariner 

 inclines to the opinion of Oiidemans'' that it may be a scent organ. The objection to this view 

 is that in the microscopic sections made and figured by Kathariner these are no traces of special- 

 ized cells like what have been found by Deegener '' in great numl>ers in the hypertrophied hind 

 til)iiv of ircpUtlus hectim, there being little doubt but that these highly moditied hind legs of this 

 genus are true scent organs. In the tibial spurs examined by Kathariner there are no specialized 

 cells besides the matrix or h}-podei'mal layer of the integument, which is, howerer, folded on the 

 anterior surface of the appendage, and consists of high cylinder cells with granular protoplasm 

 and laru'e elongated nuclei, such as Dahl'' discovered in sections of the sole of the feet of locusts, 

 and which secretes a glutinous fluid. AVhether these cylinder-cells secrete an odorous fluid is 

 prolilematical. 



Dahl has suggested that these appendages may be adapted for cleansing the antenna?, being 

 analogous to the spurs on the liml)s of other insects, especially the Hymenoptcra. In accordance 

 with this explanation Dahl alfirms that the fore-tibial spur is wanting in most butterflies 

 with a well-developed antennal knob, and is vestigial in many moths with strongly' pectinated 

 antenna\ That this appendage is in any wa,y comb-like has never occurred to us, since in the 

 syssphingine moths, as also in the saturnioids, the edges are smooth and unarmed with setie 

 coarse enough to act as the teeth of a comb. We have found these spurs as well developed in 

 the male of Telea poli/phemuK as in the Ceratocampida' or Sphingidtt; in CaJtguJa japonica 6 

 the spurs are long and narrow, but in the 9 only one-half as long and very narrow; in this sex 

 it varies in size and width, some being half as long as others, /. e.^ one-quarter as wide. In the 

 female of Sys»phin;c moJlna, however, the spurs are as large as in the male. Speyer states 

 that in the female of certain moths the spur is atrophied. The naked inner side of that of Telea, 

 and presumably in moths generally, is covered with a dense growth of very fine, stifl' microscopic 

 seta', which are short, sharp, and of even length. (See also Kathariner, figs. 4 and 5.) The 

 function of this minute growth seems problematical. In the fore tibia of Addocepluda /(wr/<?/, the 

 hair-scales are parted so as to expose the spur, the outer side of which is naked, tliough clothed 

 with a microscopic pile, the edges of the spur being densely scaled. 



An objection to the odoriferous nature of these spurs is the fact that in the Sphingidie, where 

 they arc so well developed, there occur, though not all in the same species, three kinds of what 

 appear to Ite, according to Rothschild and Jordan, undoubted scent organs. These authors 

 regard this appendage as homologous with the proximal spur of the hind tibia, but do not give 

 an opinion as to its function. Its use will have to l)e determined by careful observation. Its 

 large size and more complete development in the male shows that it somehow shares in the 

 movements of the lim])s of the forms possessing it. We have never observed any decided signs 

 of these spurs having l>cen put to any use, such as the loss by friction of the scales clothing the 

 outside and edges. 



The great size of the fore tiliiai spurs in VitJn roi'in scjntlcralis is worthy of note; this species 

 is nnicii more active than C. regalis, being not infreijucntiy attracted by electric lights. 



In the Ceratocampinte this spur seems in some genera to afl'ord good specific characters, but 

 it is of little practical use in separating either genera or families. 



" Das Scliienenbliittchen der Schwiirmer. lllustr. Zeits. Ent. IV, Xns. S, 11. ]S9n. 

 ''Die Neilerlaiiilsclie Insekten. 1897. IV, No.-. 8, U. 



"■ Das Put'torgaiu'ii von Hepialus heotus L. Zeits. wissen. Zool. LXXI, 1902, pp. 27(3-295. 

 ''Beitriige ziir Kt>iiiitniss des Banes und der Funktioneu der In-sektenbeine. 18S4. 



