STICHOCOTYLE NEPHROPIS, A NEW TREMATODE. 277 



cavity of the sucker. Nuclei are scattered through the tissue, each cell pro- 

 bably possessing one. The muscles which contract the cavity of the sucker are 

 not so conspicuous. The tissue of the sucker is separated from the tissues of 

 the body by a thin limiting membrane, which is continuous at its periphery 

 with the limiting membrane of the epidermis. This is an arrangement which 

 is not easily explained, as, the muscles of the sucker being probably a special- 

 isation of the ordinary muscles of the body wall, it would be expected that the 

 continuity between the two would be maintained. 



Beneath the lateral excretory canal of the right side, in the anterior sec- 

 tions, is an area occupied by very closely crowded nuclei. This can be traced 

 through successive sections of the series as far as the end of the fifth sucker. 

 It passes from its first position, under the right main canal, to the left side of 

 the same canal, at the same time becoming thicker, and towards its termination 

 becomes so broad as to extend beneath the intestine from the right canal to the 

 left. There is thus an irregular cord of small unmodified cells extending 

 through a considerable part of the length of the body, and it is possible that the 

 generative organs of the adult are derived from this. 



The most external layer of the body representing the epidermis and cuticle, 

 is in sections, as in the living animal, quite homogeneous. I have not yet been 

 able to distinguish in it either nuclei or cell boundaries, or a separation between 

 epidermis and cuticle. The layer becomes thinner where it lines the cavity of 

 the sucker. In the living animal small funnel-shaped openings are seen in the 

 epidermis, which may be the apertures of glands, but as they are not visible 

 in the sections it is possible that they are only fractures produced by com- 

 pression. 



The only trace of tissue which may belong to the nervous system is a tract 

 composed of very fine fibrils in some of the sections anterior to the mouth. 

 This tract forms a band extending horizontally across the body near to the 

 dorsal side. The fibrils of which it is composed are extremely minute, and the 

 whole tract is destitute of nuclei. It is shown in fig. 6, and may represent the 

 cerebral ganglion. A pair of processes from this mass of tissue can be traced 

 through the succeeding two or three sections, which are probably the rudiments 

 of a pair of lateral nerve-cords. They pass downwards towards the under side 

 of the main excretory canals. 



The cysts in which the animal occurs are scattered on the extremely thin 

 walls of the posterior part of the intestine of Nephrops, in the region of the 

 abdomen. They sometimes contain more than one worm, as many as six 

 having been taken by Mr Matthews on one occasion from a single cyst. 

 Usually the wall of the cyst is soft and opaque, and white or light yellow in 

 colour. It is of a cellular nature, and is apparently a pathological product of 

 the tissue of the intestine of the host. 



