636 WILLIAM A. HASWELL. 



the pharynx; the openings of the ducts are most abundant 

 round the anterior aperture. A complex system of nerves 

 extend through the wall of the pharynx. 



Von Graffs refers to the pharynx of Prorhynchus as 

 belonging to the same type as that of the Plagiostomidse, 

 and in his account of P. stagnalis states that it has the out- 

 ward form and probably also the internal structure of the 

 " pharynx variabilis'^ of that family. He had, however, not 

 examined sections. Vejdovsky^ states that the order of the 

 layers in P. hygrophilus is that laid down by v. Graff as 

 diagnostic of the '^pharynx doliiformis;^' but the description 

 which he gives and his figure 93 do not bear out this state- 

 ment. The order of layers in the " pharynx doliiformis/' as 

 given by v. Graff,^ is, from without inwards, longitudinal, 

 circular, longitudinal, circular; whereas the order which 

 Vejdovsky describes and figures is longitudinal, circular, cir- 

 cular, longitudinal, as in the form now under consideration, 

 though all the layers are very feebly developed, being each 

 only about one fibre in thickness. This order of the layers 

 occurs in none of the described types — that in the '' pharynx 

 variabilis" being circular, longitudinal, circular, longitudinal 

 — and would appear to be characteristic of the family Pro- 

 rhynchidse. 



The intestine extends to very near the posterior extremity 

 of the body. Anteriorly it gives off on the ventral side a short 

 and wide diverticulum, which passes forwards for a short dis- 

 tance below the posterior extremity of the pharynx. Laterally 

 it is divided throughout its entire extent by constrictions 

 brought about by ingrowths of the investing fibrous layer of 

 the intestinal wall. Of these there are about forty on each 

 side. On the right side they correspond very closely with the 

 windings of the ovary. The epithelium of the intestine consists 

 of extremely long narrow cells of very irregular shape, many 

 of which are filled with the large granules so characteristic of 



^ Loc. cit., pp. 87 and 265. 

 2 Loc. cit., p. 148. 

 ' Loc. cit., p. 84. 



