FISH PARASITES COLLECTED AT WOODS HOLF. 271 



namely, one chicken wing with the leathers on it, two slices of beefsteak, a few pieces of cucumber 

 rind, two large pieces of "sea pork," a piece of rope yarn, partly raveled out, with other debris. 

 Evidently a bucket of waste from the cook's galley of some passing vessel had been thrown over- 

 board, and the shark had scooped up the whole mess. 



Large numbers of Thysano<-<'i>halnm cris^um (Cestode Parasites <>!' Fishes, p. 1 IS), large and small ; 

 with enormous numbers of free proglottides in the spiral valve. The scolices were, found attached to 

 the mucous membrane. The pseudobothria, in such cases, were expanded into a Hat fimbriated disk 

 and closely adherent to the mucous membrane. These cestodes were counted and a number of them 

 measured. There were 56 with mature proglottides and 238 young. The latter ranged in length from 

 30 to 300 mm. The average of 11 representative forms was 12S mm. Strobiles, which had ripe pro- 

 glottides, measured 1.25 meters. This represents an actual total length of something like 100 meters; 

 or, allowing for the maturity of the small specimens, a potential length of 3(57 meters (approximately 

 J mile), without taking into account the free proglottides, of whicfh there were immense numbers. 



Acanthocheilus nidife.r sp. nov. (see Part II, page 303, for description) in crypts in stomach-wall 

 and free in pylorus. 



(2) August 19; one (2.5 meters in length); stomach contained numerous jaws of squids, some 

 of them of good si/e; various bones, skull of a lish, numerous ear-bones of lish, the operculnm of a 

 mollusk (Lunatia), seaweed (Fncus), sand and gravel, and a nondescript piece of animal tissue about 

 the size of one's hand, probably the remains of the pectoral fin of a goose-fish. 



Large numbers of Thi/sanocephalnm crispum, as in every specimen of this shark I have examined, 

 in spiral valve. Also a few small forms not yet identified, heads resembling those of the genus Spon- 

 giobothrium. There is, however, a tleshy anterior median eminence on the head. The worms are 

 small, and before killing exhibited a tendency to become convoluted. 



There were also several free proglottides of an altogether different kind from those of Thysano- 

 cephalum, of which, as usual, there were enormous numbers. The eggs of Thysanocephalum are fusiform 

 in shape, an unusual form among cestode eggs. 



Tetrarhynchns bicolor (Larval Cestode Parasites of Fishes, pp. 813-815, pi. LXVIII, tigs. 1-6), 36 

 specimens, firmly attached to stomach-wall, where they had formed deep pits, extending into the mus- 

 cular layers. Head and neck white, back of collar yellowish. These specimens, when removed from 

 their host and placed in sea-water, contract and expand actively and assume a great variety of shapes. 



Two imperfect strobiles without scolices were found in the stomach. Upon sectioning they were 

 found to be identical with sections of Thysanocephalum and were so identified. I do not know how to 

 account for their presence in the stomach. 



Acanthocheilus nidi f ex as in shark examined on August 11. 



Pathological conditions of pylorus of Galeocerdo tiyrinus. The pylorus of each of the specimens of 

 leopard shark examined was occluded by what appears to be a colloid tumor developed in the stib- 

 mucosa, pi. 42, fig. 102. Although occurring in different places in the two cases they were of the 

 same essential structure in each. A brief description of the first is given. The tumor was first 

 encountered at its anterior end while slitting the pylorus with scissors from the anterior end. It 

 presented a smooth globular stopper-like surface, which apparently completely occluded the lumen of 

 the pylorus. No passage could be found on passing a probe around the periphery of the tumor. On 

 cutting into the lumen at the posterior end of the tumor a narrow passage was discovered, which led 

 back beside the tumor and proved to be continuous with the lumen of the pylorus. This narrow 

 passage diverged from the lumen a short distance in front of the tumor. Two raised folds of epithe- 

 lium, parallel with each other and lying longitudinal to the axis of the pylorus, led into the passage. 

 The anterior end of the tumor lay 24.5 cm. back of stomach. It was about 9 cm. in length and 2.6 cm. 

 in diameter at its anterior end, its posterior end about 9 cm. in front of the entrance of the bile duct. 

 These dimensions include the mucous membrane, which was pushed into the lumen by the developing 

 tumor. The anterior end was the larger, and the diameter grew gradually less to the posterior end, 

 which terminated in a blunt point. The passage, which remained open, was very narrow, and its epithe- 

 lium had a different appearance from that of the lumen, both before and behind the tumor. 



In the shark examined on August 19 a similar tumor was found about midway of the length of 

 the pylorus, also with a narrow passage beside it. The main lumen was also interrupted at other 

 points. I find no mention of such structures in notes made in former years on examinations of this 

 shark, and have no recollection of seeing anything like them before. 



