134 PROCEEDINGS OF THE jSTATIONAL MUSEUM vol. S3 



Superfamily Phyllobothrioidea Southwell, 1930 



SCOLEX PLEURONECTIS Mulier. 17S8 (S. POLYMORPHUS Rudolphi, 1819. of many writers) 



Larval cestodes of this species have been found in a great num- 

 ber of different marine fishes and show a considerable variation in 

 size and form, but the variation among the individuals in a single 

 host and changes that are thought to take place with age make it 

 extremely difficult, and at present impossible, to separate different 

 species with any degree of accuracy. These worms have been consid- 

 ered to be the larval forms of various tetraphyllidean worms by dif- 

 ferent authors; among the supposed parent worms are species of 

 Acanthohothrium, G alliohotliriwm^ Onchobothrtuin^ Echene'iboth- 

 rmm^ and Phoreiobotlirium,. Experimental feedings of the larvae 

 to elasmobranch hosts have been made by Monticelli (1888) and 

 Curtis (1911). Monticelli, feeding larvae from a flounder {^Arno- 

 glossus) near Naples to a species of Torpedo^ obtained young speci- 

 mens of CaUiohothrlum filicoUe^ which he believed to have developed 

 from the larvae fed. Curtis, on the other hand, fed larvae obtained 

 from Cynoscion regalis at Woods Hole, Mass., to C aroharias littoralis 

 and obtained young specimens of Phoreiohothrlum triloculatum^ 

 which he believed to have been derived from the experimental feed- 

 ing. Southwell (1925) sums up the situation as follows: "There 

 can, I think, be little doubt that the name Scolex polymorphus does 

 not indicate a definite species; it is a group name which includes a 

 number of different species in the final host," 



Linton in his various papers has noted the occurrence of these lar- 

 val cestodes, which he lists under the name Scolex folymorplius^ in 

 over 60 widelj' diversified species of fish. In some hosts (e. g., Cyn- 

 oscion regalis in New England) they were found in almost every 

 specimen examined and in enormous numbers, either in the cystic 

 duct and gall bladder or in the intestine, or in both. The forms de- 

 scribed from various fish hosts are by no means all alike. They dif- 

 fer in size, in the form of the sucker, or " myzorhynchus ", at the 

 anterior end between the bothria, in the size and shape of the both- 

 ria, in tlie presence or absence of cross partitions, or " costae ", on 

 the bothria (one to four in number whe^ present), and in the pres- 

 ence or absence of red pigment })atche8. Linton (1905) records 

 this })arasite from Gdleichthys niilherti at Beaufort, N. C. Twelve 

 specimens were obtained from the cvstic duct near its junction with 

 the intestine. Of these Linton says : " The sj)ecimens contracted 

 freely between 4 and 8 nnn in length. At rest, with bothria re- 

 tracted, the length was about 1.2 mm. There was no indication of 

 costae on the bothria nor of the red pigment patches often noted in 

 these larval cestodes." Similar specimens were found in the intes- 

 tine of another liost of the same species. 



