162 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 Heterakis 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. foveolata. 
A species of Ichthyonema was found on three different dates in the 
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 cesophagus 
and a diverticulum from the anterior end of the intestine. 
One very singular form was found in Chlorichthys bifasciatus, which 
had a subglobular, chitinous pharynx which was marked with spiral ribs 
running from left to right anteriorly, thus crossing in optical section. 
Cestodes.—The larval forms usually referred to by the name Scolex 
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- 
rium were found in eight of the species of fishes examined. KR. speciosum 
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 (Poronotus triacanthus) of the northern coast, or of the 
hound-fish (Tylosurus acus) 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: Acanthobothrium brevissime sp. 
nov., Anthocephalum gracile, Phyllobothrium folatum, Spongiobothrium 
variabile, Synbothrium filicolle, two species of Rhinebothrium 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 9-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. 270, 271, 425). 
Again, there were a large number of both adult and young and free 
ripe joints of the singular cestode Thysanocephalum crispum. In all the 
tiger-sharks which I have examined in the Woods Hole region I have found 
