114 REPORTS OF INVESTIGATIONS AND PROJECTS. 



Prof. Edwin Linton continued his studies of the parasites of fishes and 

 other animals at Tortugas with admirable success. His results are important 

 from an economic as well as from a purely scientific standpoint. Professor 

 Linton's skill as an observer is unexcelled in this field among American zoo- 

 logists. His preliminary report of this summer's work is as follows : 



Preliminary Report on Animal Parasites, by Edwin Linton, Washington and 



Jefferson College. 



During my stay at the laboratory, June 27 to July 19, I continued work on 

 the helminth fauna of the Tortugas, with especial reference to the entozoa of 

 the reef fishes. As in 1906, so this year, I found very few acanthocephala and 

 nematoda. Encysted cestodes were also found to be of less frequent occur- 

 rence than they are at Beaufort or on the New England coast. Trematodes 

 were more abundant than the other orders, and there is reason to think that 

 they are more prolific in species than they are in northern waters. 



One form of distome, found rather frequently in the grunts and sparingly 

 in a few other fish, is peculiar in that its ova are provided with a long fila- 

 ment. The species has not yet been determined. It does not agree with 

 any of the genera in Pratt's Synopsis. 



Many species of distomes were added to last year's list. Thus the 3 speci- 

 mens of spotted moray (Lycodontis moringa) yielded 5 species of distomes 

 not found in this host last year ; and 3 black angel-fish (Pomacanthus arcu- 

 atus) yielded 3 species which were not found in the specimen examined last 

 year, wrongly recorded under the name Chcrtodipterus faber. 



No selachians were taken while I was at the laboratory this year. One 

 small nurse-shark (Ginglymostomwn cirratiim) had been taken before my 

 arrival, from which were obtained a few specimens of a species of Ascaris, 

 not found last year, and 2 species of cestodes similar to forms collected from 

 this host last year. After I left the laboratory, Mr. Davenport Hooker col- 

 lected from a cub-shark (Carcharhinus lamia) some cestodes, which I have 

 since examined. As I have already made a report on the cestodes collected 

 in 1906, I take this opportunity of recording the cestodes from this species 

 of shark, which is not included in last year's list : 



Crossobothrium angustum, or near it; 3 scoleces and a few fragments, 



from the spiral valve. 

 Phoriobothrium lasium, 15, from the spiral valve. 

 Otobothrium penetrans, i adult from stomach. This name was given 



to an immature form found in the flesh of the gar (Tylosurus acus) 



in Bermuda. This is therefore the first record of the adult of this 



species. 



In the Year Book of the Carnegie Institution for 1906, page 1 16, I stated 

 that the spiral valve of a shark which had been kept in formalin until my 

 arrival at the laboratory belonged to a tiger-shark {Galeocerdo tigrinus). 

 As the identification was a somewhat unusual one, being based in large part 

 on the character of the stomach contents and the entozoa, I embrace this 

 opportunity of confirming the identification. Having learned from Dr. 

 Mayer that the jaws of the shark in question had been sent to the museum 

 of Harvard University, I wrote to Prof. Samuel Carman, who replies that 

 the jaws are the jaws of Galeocerdo tigrinus. 



