1 62 Papers from the Marine Biological Laboratory at Tortugas. 



shark, a species of Ascaris, were firmly attached to the stomach-wall, their 

 heads penetrating at least as far as the muscular layer. 



Representatives of the genus Hetcrakis were found sparingly in the 

 green moray, gray snapper, spot, and hog-fish. Some of those from the 

 gray snapper and one from the spot agree closely with H. fovcolata. 



A species of Ichthyonema was found on three different dates in tire 

 ovaries of the gray snapper; one was also found in the gar. 



Immature nematodes were found, usually encysted on the viscera, in 

 the following fishes : Barracuda, yellow-grunt, yellow-tail, grouper, cabezote. 

 white grunt, striped grunt, black grouper, yellow-finned grouper. In all 

 cases the number of these immature nematodes was few. The most common 

 type was characterized by having an elongated basal bulb on the oesophagus 

 and a diverticulum from the anterior end of the intestine. 



One very singular form was found in Chlorichthys bifasciatns, which 

 had a subglobular, chitinous pharynx which was marked with spiral ribs 

 running from left to right anteriorly, thus crossing in optical section. 



Ccstodes. The larval forms usually referred to by the name Scole.v 

 polymorphus are not so abundant as they would be in an equal list of north- 

 ern fishes. Only a few were seen and only in the gray snapper, yellow-tail, 

 grouper, and frigate mackerel. 



Encysted stages, belonging for the most part to the genus Rhynchoboth- 

 riitin were found in eight of the species of fishes examined. R. speciosiiin 

 was recognized in a number of instances. Encysted cestodes were found 

 only on the viscera. No cases of flesh parasites comparable with that of 

 the butter-fish (Poronotns triacantlnis] of the northern coast, or of the 

 hound-fish (Tylosurus acits} of Bermuda, were met. The selachians here 

 as elsewhere are bearers of many species of adult cestodes, whose favorite 

 place of lodgment is in the spiral valve. 



I had the opportunity of examining but one sting-ray and that a small 

 specimen. It yielded, however, a list of nine species of cestodes belonging 

 to seven genera. This list is as follows: AcantJiobotliriwn brevissime sp. 

 nov., Anthocephalum gracilc, Phyllobothrium foliatum, Spongiobothriwn 

 variabile, Synbothrium filicolle, two species of RhinebotJiriiini and two spe- 

 cies of Rhynchobothrium. It may be inferred therefore that the sting-ray, 

 if a sufficient number were to be examined, would yield as long a list of 

 entozoa as it does at Beaufort or Woods Hole. 



Some interest may attach to the fact that one lot of parasites is credited 

 to the tiger-shark in the table, although the shark from which they were 

 obtained was not identified. 



On June 2, before my arrival at the laboratory, a p-foot shark was cap- 

 tured. Its spiral valve was opened and placed in 5 per cent formaldehyde. 

 Upon examining this material I decided that it had come from a tiger-shark. 

 As this is an unusual method of identifying a fish it may be worth while to 

 record my reasons for having confidence in this identification. In the first 

 place, the valve itself is of the same type as that of the tiger-shark. This 

 fact, however, does not exclude the cub-shark, which is common in these 

 waters. In the second place, the varied contents of the stomach (see table) 

 agree with what has been recorded for this species (U. S. Fish Commission 

 Bulletin for 1899, PP- 2 7> 2 7 l > 4 2 5)- 



Again, there were a large number of both adult and young and free 

 ripe joints of the singular cestode Thysanocephalum crispnm. In all the 

 tiger-sharks which I have examined in the Woods Hole region I have found 



