54 MEMOIKS OF THE NATIONAL ACADEMY OF SCIENCES. 



and Jordan, the Chalcosiid®. While the statement i.s made that all the Lepidoptera below the 

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

 interesting to ascertain whether there may not be here and there cases of its absence in scattei'ed 

 genera, and perhaps subfamilies, of the moths. 



Kathariner" has recently published an excellent article, for the tirst time describing the 

 structure and tine anatomy of this appendage in Acherontia afropos, Deilephila elpenor, and two 

 species of Sphinx {S. convolvull and S. ligustri). i 



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

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

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

 ized cells like what have been found by Deegener'' in great numbers in the hypertrophied hind 

 tibi» of ITepialus hectus, there being little doubt but that these highly modified hind legs of this 

 genus are true scent oi'gans. In the tibial spurs examined by Kathariner there arc no specialized 

 cells besides the matrix or hj'podermal 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 large elongated nuclei, such as Dahl'' discovered in sections of the sole of the feet of locusts, 

 and which secretes a glutinous fluid. Whether 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 limbs of other insects, especially the Hymenoptera. In accordance 

 with this explanation Dahl affirms that the fore-tiliial 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 way comb-like has never occurred to us, since in the 

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

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

 the male of Telea polyphemus as in the Ceratocampidse or Sphingidfe; in Caligula ja])on[ca 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-cjuarter as wide. In the 

 female of Si/ssp/iltix molina, 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 innei' side of that of Telea, 

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

 setfe, 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 Adelocephula JkikjcI, the 

 hair-scales are parted so as to expose the spur, the outer side of which is naked, though 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 Sphingidse, where 

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

 appear to be, 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 be determined by careful observation. Its 

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

 movements of the limbs of the forms possessing it. We have never observed any decided signs 

 of these spurs having been put to any use, such as the loss by friction of the .scales clothing the 

 outside and edges. 



The great size of the fore tibial spurs in Vithnronla sepuleralis is worthy of note; this species 

 is much more active than ('. regal is, being not infrequently attracted by electric lights. 



In the Ceratocampinse this spur seems in some genera to afford good specific characters, but 

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



« Das ScliienenbUittcheii der Schwiirmer. lUustr. Zeits. Ent. IV, Nos. 8, 11. 1899. 

 '> Die Neaerliuulsche Insekten. 1897. IV, Nos. 8, 11. 



■■DaM Diiftortjam'n von Hepiahis hectus L. Zeits. wisseu. Zool. LXXI, 1902, pp. 276-29.5. 

 ''Beitriige ziir Kenntniss des Baues mid der Funktioneii der Insektenbeine. 1884. 



