ON TWO PARASITIC FORJifS OF TETUARnTNCllIU^. 329 



a tendency to form three rows ; while the bones of the digits differ 

 chiefly in the small number of bones in each, and iu there being 

 four digits on the ha,nd and five on the foot. 



The Anatomy of two Parasitic Forms of the Family Tetrarhyn- 

 chidae. By Francis H. Welch, F.E.C.S., Surgeon, Army Me- 

 dical Department, and Assistant Professor of Pathology, Army 

 Medical School, Netley. Communicated by Professor Busk, 

 V.P.L.S. 



rHead May 6, 1874.] 



(Platks XXIV.-XXVI.) 



These two forms of the Tetrarhynch family, suborder Cestoda 

 (Cobbold), among parasites, were obtained from the stomach of a 



Shark (Carcharias ■ ?), and transferred to me by Dr. Mac- 



donald, E.N., F.E..S. Of the larger form there were three speci- 

 mens, of the smaller five ; and with them was a portion of the 

 shark's stomach, to which one of the larger forms was attached, 

 the rest of the parasites being loose in the alcohol in which the 

 whole mass was preserved. 



The mucous membrane of the stomach was irregularly superfi- 

 cially ulcerated in spots to the size of a shilling ; and narrow chan- 

 nels diverged from the surface of the ulcer into the subjacent 

 tissues to the depth of y^^ to j\j% of an inch, these channels gene- 

 rally being arranged in pairs and evidently produced by the pro- 

 boscides of the parasites for anchoring themselves ; while with 

 some there was also a broader pit, from which the channels diverged, 

 produced by the partially immersed head of the creature. Around 

 these channels for at least | an inch there was marked dark dis- 

 coloration of the tissues from blood-extravasation and disintegra- 

 tion. One of the larger forms was still attached ; but since the 

 stomach had been cut into pieces it had moved ; for it was 

 now anchored to the fresh incised surface. No part of the head 

 of the parasite was inserted into the stomach-coats, so that the 

 suckers were not called into action ; but the proboseides diverged 

 from each other into the tissues, having a broad base of attach- 

 ment ; and a considerable application of force relative to the size 

 and strength of the tissues of the creature was used without the 

 anchors giving way. 



Whether these forms of animal life are new to science or have 



2-J:* 



