﻿Sept. 1895] Packard. Scent Glands of Insects. 119 



While describing the living larva of Perophora inelsheinicrii my 

 attention was called to some small singular sternal tubercles on the two 

 hinder thoracic segments ; but I did not, to my regret, then carefully 

 examine them. On farther examination of two alcoholic specimens, 

 however, I find that the tubercles guard the lips of an eversible gland. 

 They are most distinct on the third thoracic segment, where there are 

 to be readily found four dark prominent papillae, two on each side of 

 the median line of the body, directly behind the base of the legs. The 

 heads of the papillae are dark and finely granulated. The two tubercles 

 on each side touch each other ; they are probably modified piliferous 

 warts. These four papillae enclose a square area in the middle of which 

 are the lips, arranged transversely, of the mouth of an eversible gland. 

 These organs are also present on the second segment, and are of the 

 same degree of development. Whether there is the opening of a func- 

 tional sternal eversible gland on the first thoracic segment I am uncer- 

 tain, as I have been unable in my two alcoholic specimens (one of which 

 had died and shrivelled up) to detect any traces of lips. On this seg- 

 ment the base of the legs are close together, the basal joints being large 

 and closely contiguous. There are no tubercles developed like those on 

 the second and third segments, and in the material at my disposal I 

 have been unable to find an opening. It is not improbable, however, 

 that such a gland with lips once existed in the ancestors of this and of 

 Lacosoma, for in JVola, which is a member of a family probably much 

 later in appearance, there are two well developed sternal glands. Ir 

 several Notodontians one is well developed on the under side of the 

 first thoracic segment, while there are none behind. Probably in the 

 Perophorinae, owing to the modifications of the body, due perhaps to 

 their constructing a case and thus causing some change in the move- 

 ments of the first pair of legs, they are much nearer together than usual 

 in larvre not thus adapted to living in cases. 



In Lacosoma homologous papillae are present in the corresponding 

 segments, but whether the external opening of the gland is present I 

 am unable as yet to state. On the third thoracic segment there are four 

 tubercles present in the same general position as in Perophora. The 

 anterior pair, however, are very small, and (antero-posteriorly) remote 

 from the hinder pair. The latter are much larger than the front pair 

 and in the form of small, rather slender papilliform tubercles, and 

 armed at the end with several crowded spine-like granulations. Be- 

 tween them is to be seen in my single alcoholic specimen a depression, 

 but I cannot detect any lips or any opening. On the second thoracic 



