de;partme;nt of marine biology. 125 



species. The spiral valve, which had been preserved in formalin, yielded 5 

 species of cestodes, all of which were found in the stingray which was exam- 

 ined in 1906. The two species of spotted stingray were the first of the eagle- 

 rays that I have had the opportunity of examining for many years, and it is 

 the first time that I have seen this species. 



PARASITES IN FLESH. 



In carrying out a line of investigation begun for the U. S. Bureau of Fish- 

 eries I made a careful search for flesh parasites in practically all the fish 

 which were examined. The only fish parasites found were in the following 

 fish: 



Mycteroperca vcnenosa. — A few degenerate cysts in flesh near the back- 

 bone. 



Calamus calamus. — 2 small distomes encysted in the flesh of one fish above 

 the backbone; a cestode (Synbothrium UlicoUe) in about the same situation 

 in another. 



Acanthocephala. — As in previous years, representatives of this order were 

 found but sparingly. They were found in but 7 of the 32 species of fish 

 which were examined, and in every case few or even only i was found. But 

 I species was found. This appears to be identical with the one which I have 

 recorded under the name Bchinorhynchus pristis, which appears to be a spe- 

 cies with a southern range. A comparison of the Acanthocephala collected 

 at Bermuda, Beaufort, Tortugas, and Woods Hole justifies the conclusion 

 that the Acanthocephala of marine fishes have their greatest development in 

 species, and particularly in individuals, in northern fishes. 



Nematoda. — Like the preceding order, this is rather sparingly represented 

 among Tortugas fishes. Immature, encapsulated forms were found in only 

 7 species of fish, and very sparingly in all of these except the rockfish (Myc- 

 teroperca veiienosa). This also is in contrast with the distribution of imma- 

 ture nematodes in northern fishes where they are of frequent occurrence on 

 the viscera of a large number of species, and often in large numbers. The 

 immature forms, so far as they have been studied, are characterized by hav- 

 ing a cylindrical cesophagus with an elongated bulbous base and a short in- 

 testinal diverticulum directed cephalad and lying beside the oesophagus. 



Adult nematodes were found in 6 species of fish, but only one or two in 

 each case. For the most part those from teleosts belonged to the genus 

 Heterakis, while those from the nurse-shark belonged to the species acan- 

 thocheilus. 



Cestoda. — Encysted and larval forms were found in 11 of the species of 

 fish which were examined this season. In no case were they numerous. It 

 is worthy of note that the larval forms known as Scolex polymorphus, which 

 are found in a large number of the fishes of Beaufort and Woods Hole, were 

 found in only 2 of the Tortugas fishes, and but few in each host. These 

 forms represent neither the encysted stage nor the adult stage, but rather a 

 condition of transient residence made possible by their powers of resistance 

 to the intestinal juices of their temporarj^ hosts. The scarcity of these para- 

 sites at Tortugas, therefore, which is parallel with what was found to be the 

 case at Bermuda, is dependent rather on the conditions incident to a coral 

 reef than to the real absence of the parasites themselves from the region. In 

 their adult condition they are found in the selachians and in their encysted 

 stages they occur in teliosts, crustaceans, etc. So far as I have studied the 



