INTERNAL ANATOMY OF THE MOTH. 55 



point is still unsolved. Since the organ is not for sucking, as long sup- 

 posed, and is evidently not digestive, it seems likely, or at least pos- 

 sible, that it serves simply as a reservoir. It is first developed in the 

 pupal stage. 



In a lateral view, as in Fig. 2, the neck of the reservoir is concealed 

 by the anterior end of the stomach, which projects into two short lobes 

 on each side of the neck. 



The stomach, s#, is very much smaller than in the larva, for it barely 

 extends through four abdominal segments. Its walls have the same 

 two muscular coats as we have described in the larval stomach, vide 

 supra, and the epithelial lining is thrown up into beautiful glandular 

 corrugations. The stomach is overlaid with the convoluted malpighiau 

 vessels, mv, six in number, three of which, on each side, unite and 

 open by a short, common duct into the posterior end of the stomach. 

 At the end of the stomach begins the peculiarly coiled small intestine, 

 ij which passes to the left of the bursa copulatrix in the female, and of 

 the genitalia in the male. The intestine passes into the wide terminal 

 division, or rectum, B, from the front end of which runs out a curved 

 blind pouch or caecum, c. In Danais the terminal division is clearly 

 separated into an anterior part or colon, and a posterior part, or true 

 rectum, but the rectal region is less noticeable in Aletia. 



The course of the aorta, or anterior extension of the heart, in lepi- 

 doptera, was not correctly described by the older authors. Burgess ob- 

 served its strange bend in the butterflies, and has since studied it in 

 several forms of lepidoptera, and published his results in a short paper.* 

 In this article he describes and figures the course of the thoracic aorta 

 in a noctuid. In Aletia it enters from the abdomen behind, bends im- 

 mediately upwards, widens rapidly, makes a slight crook, and then, 

 reaching the dorsal wall of the metathorax, to which it is secured by 

 fibrous tissue, it makes a sharp bend and runs back upon its own course; 

 next curves forwards, and, growing gradually narrower, runs along just 

 above the (BSOi)hagus into the head, passing with the former through 

 the brain. 



The nervous system consists of a chain of ganglia and the nerves. 

 The sujira-oesophageal ganglion, or brain, occupies nearly the center of 

 the head (Plate YII, Fig. 2, Br.), and is connected by very thick commis- 

 sures with the sub-cesophageal ganglion, which j)asses gradually into 

 the cord that leads to the first thoracic ganglion. This is quite distinct, 

 but the second and third are almost completely fused, and connect with 

 the abdominal ganglia by a very long commissure. In the abdomen 

 {Plate YIII, Fig. 2) there are four nerve centers {a. g., a, g.), as is almost 

 always the case in the Lepidoptera, lying in the third, fourth, fifth, and 

 sixth segments respectively. The last is the largest, and is compounded 

 of two or more ganglia fused together; the principal nerves arising from 

 it seem toiunervatethe organs of reproduction. 



* Burgess. E. Proceedings Bost. Soc. Nat. Hist., XXT, 153-156. 



