ENTOMOSTKACA OF MINNESOTA. 127 



plate, above and between the stylets. ]S'o special divarications or cseca 

 are appended to the digestive tract, and the only other organ which is 

 at all considered to belong to the alimentary system, is what is known 

 as the "shell-gland," present in most crustacse, but till recently 

 thought to be absent in Canihocamptus. It is a coiled tube found in 

 the lower part of the first segment of the thorax. It is impossble to 

 find this organ in Ccmthocaniptm, in every case, it being very obscure; 

 and its office is uncertain, though it is supposed, perhaps with little 

 reason, to be hepatic in function. 



There is no functional heart in this animal, but its place is taken 

 I)y a peculiar apparatus, hitherto undescribed; this consists of a tube, 

 surrounding the posterior portion of the alimentary canal. This sac 

 around a sac is open in front, and serves by a double mechanism the 

 office of a pulsating heart, though in a very imperfect manner. 



There are no true haematic or lymph corpuscles in this animal; 

 so far, at least, none have been discovered. The place of these 

 blood corpuscles is taken by globules of yellowish or red color of 

 the most diverse size. These nutritive globules, or fat globules, as 

 they have been called, are undoubtedly reservoirs of nutriment in a 

 shape convenient for the animal's use, and equally certainly are 

 derived from the contents of the intestine. In those Gox)epoda which 

 have a functional heart, it is open anteriorly into a general body- 

 cavity in the same way as in this animal. That a portion of the vas- 

 cular system should surround the alimentary canal is no unexampled 

 thing, for in Daphnia a large sinus embraces a portion of the canal. 

 The same provision as this described in Cantliocaynptus occurs in the 

 CydopidcB. The nutritive globules are often very large, and are fre- 

 quently extremely abundant, especially in females soon to become 

 gravid. Three-hundredths mm. is not a large measurement for the 

 diameter of such drops. 



The nervous system is very hard to trace, consisting of a large 

 pear shaped ganglion just below the eye, from which extend commis- 

 sures around the oesophagus, connecting them with the ventral ganglia 

 lying between the bases of the feet. The senses are not apparently 

 well developed, for, excepting the eyes, we cannot locate with certainty 

 the organs of any sense. There are, however, two spots which are 

 evidently devoted to special sense: first, the processes on the fourth 

 joint of the antennae, which may be simply the seats of tactile sense, 

 or may have nerves suitable for perceiving chemical stimuli; second, 

 the area on the forehead bordered by a raised line and covered with 

 little pits, each with a small bristle. The character of this organ can 

 be but conjectured; it may be homologized with the frontal nervous 

 organs of the Vladocera. 



