Helminth Fauna of the Dry Tortugas. 175 
by the head and neck, which are so small as to be easily overlooked by the 
collector. In its expanded condition this peculiar organ is a disk with 
fimbriated edges. Each of the primary divisions has a tendency to divide, 
some of them nearly to the base. The diameter of the central, undivided 
part is 4 mm. The radiating divisions and the undivided central portion 
are all profusely frilled and folded. The minute scolex is often lost in 
detaching the worm from the mucous membrane of its host. 
16. Scolex polymorphus Rudolphi. 
Report U. S..¥. C., 1886, pp. 3, 4, plate vi, figs. 8 0: Proc. U. S. Nat, Mus., 
vol. xIx, pp. 789-702, plate 1, figs. 4-15. Bull. U. S. F. C., 1890, pp. 270- 
284, and 413, etc., noted under 28 hosts. Bull. Bureau of Fisheries, vol. 
XXIV, p. 332, etc., noted under 34 hosts. 
The literature of this title is very extensive. Without doubt it has 
been used as a specific name to designate the larve of a great variety of 
cestodes belonging to many different genera. It is a convenient term, how- 
ever, and in my papers is to be understood to refer to small larval cestodes 
found free in the alimentary canal and bile-duct of many fishes. 
Since these forms are evidently possessed of great powers or resist- 
ance to the digestive juices of fish in general, they doubtless often pass a 
longer or shorter time of sojourn in each of many hosts, related to each other 
as eater and eaten. Ultimately they attain the adult state in some selachian. 
These larve were not found in many of the Tortugas fishes which were 
examined in the season of 1906, nor were they at all abundant in those 
situations in which they were found. 
Following is a list of the finds of this larva: 
July 7.—A few small larve were found in the intestine of a grouper 
(Epinephelus striatus). The bothria were without coste, and there was 
no red pigment in the neck. 
July 10.—Several larve were observed in washings from the alimentary 
tract of a frigate mackerel (Auxis thazard). These were small, active, 
with no red pigment, but with a distinct costa on each bothrium. 
July 11.—Several small larvze were seen in washings from the alimentary 
canal of a black grouper (Mvycteroperca bonact). 
July 5 and 9.—A few were found on the first date and several on the 
second in the gray snapper (Lutianus griseus). They were small, active, 
with prominent and distinct anterior sucker, and simple bothria. The water 
vascular system was distinct, especially at the posterior end. 
July 6—A few were found in the yellow-tail (Ocyurus chrysurus). 
These were small, with the rudiments of a costa on each bothrium, and two 
small red pigment spots in the neck. They were very active. 
