L893.] NATURAL SCIENCES OF PHILADELPHIA. 423 



chamber of nearly one-half of the larger individuals of C. bartonii 

 that I have examined. It appears never to leave the branchial 

 chamber during the life of the crayfish, except at the time of moult. 

 The cocoons are found throughout the year attached to the branchial 

 filaments, especially the inner ones. Philadelphia, Pa. and Watauga 

 Co., North Carolina. 



B. pulcherrima, sp. dov. 



Fig. 2a, Plate XII, outline of the entire animal as seen from the 

 side, showing the adhesive organs on the eighth and ninth segments, 

 x23. Fig. 2b, the same specimen from the dorsal aspect, with an outl 

 ine of the alimentary canal, x23. These drawings are from a 

 medium sized preserved specimen. Fig. 2c, one of the jaws of the usual 

 form, x200. Fig. 2e, a cocoon, x45. 



The beautiful transparency of the anterior segments, which enables 

 one to see with great distinctness the internal organs of that region 

 suggested the name given to this species. 



Form rather stout, the body depressed, especially in the posterior 

 region. The segments increase regularly in width to the seventh, 

 which is the broadest; and behind which they rapidly narrow to the 

 acetabulum. Each post-cephalic segment consists of an anterior 

 larger and a posterior smaller annulus. The ventral surfaces of the 

 eighth and ninth segments are strongly flattened, and each bears on 

 its extreme lateral margins a cup-shaped adhesive organ, into the 

 central depression of which a conspicuous gland opens. These are 

 directed ventralward and doubtless serve as accessory organs of 

 attachment to aid the rather weak sucker. Those on the eighth 

 segment are usually the larger, but a considerable range of variation 

 is exhibited in this respect. The structures become proportionally 

 larger and more conspicuous in older individuals. 



The head is urn-shaped, slightly longer than broad in preserved 

 specimens, and its greatest width less than or just equal to that of the 

 first body segment. The breadth of the head varies greatly with the 

 degree of contraction of the specimen, but in the living individual 

 always appears narrow, and to form part of the generally even 

 tapering outlines of the body, never abruptly expanded as in B. 

 instabilia. The oral region is separated from the cephalic region by 

 a deep constriction, which completely encircles the head. The 

 mouth is enveloped by a pair (dorsal and ventral) of distinct thick 



