274 MR J. T. CUNNINGHAM ON 



low power, it presents the appearance shown in Plate XXXIX. fig. 1. The 

 ventral series of suckers is seen along the median line ; each of them has a 

 central depression varying in size according to the state of contraction, and 

 round this is the projecting rim, in which can be seen the radiating muscles by 

 which the sucker is dilated. The number of suckers present varies in different 

 individuals according to their age and size, — the smallest specimens, such as the 

 one shown in fig. 4, may have as few as 7, the larger usually have 15 or 16, 

 while in the largest I have counted as many as 22. No doubt specimens 

 might be found the totals of whose suckers would supply all the intermediate 

 numbers between these. 



The suckers are always more difficult to distinguish at the posterior end of 

 the series, where they are very small, and they evidently increase in number 

 at this end, just as the segments of a Chaltopod. It is this approach to meta- 

 merism which renders the creature specially interesting. The metamerism, 

 however, does not extend to any of the other organ systems, and consequently 

 the animal cannot claim among the Trematodes so isolated a position as the 

 Gunda segmentate/,, described by Lang, among the Turbellarians. From the 

 disposition of the system of suckers, I have named the animal Stichocotyle, 

 adding Nephropis for the specific name, from the name of its host. 



The surface of the body is marked by closely set transverse folds, which are 

 indicated in fig. 1, between the suckers. These folds, seen in optical section, 

 give the body a crenated outline, which is also indicated in the figure. When 

 the body is much extended, either by compression or by the muscular move- 

 ments of the animal, the folds disappear ; they are probably due to the pre- 

 sence of an inelastic cuticle, although neither in the opticle nor actual section 

 of the integument can a separation between cuticle and epidermis be dis- 

 tinguished. The external layer of the body wall, as seen in optical section 

 in the living animal, is homogeneous and transparent, and of considerable 

 thickness. 



The most conspicuous of the internal organs are the main canals of the 

 water-vessel, or excretory, system. These are two in number, one running 

 down each side of the body through its whole length. Their size, in compari- 

 son with that of the whole animal, is extremely large ; their walls are thrown 

 into transverse folds. The interior of the canals is crowded with large spherical 

 concretions similar to those found in the excretory system of other Trematodes 

 and of Cestodes. These concretions, during the examination of the living 

 animal, are continually moving with considerable rapidity, the contractions of 

 the body forcing them suddenly from one part of the canal to another. In the 

 middle line, between the main excretory canals, is the intestine. From the 

 mouth can be traced a narrow oesophagus, dilating into a muscular pharynx, 

 with thick walls, and this leads into an intestine which diminishes slightly in 



