32 Papers from the Marine Biological Laboratory at Tortugas. 



II. From Chlorichthys bifasciatus. 



It will be observed that the most striking difference between this 

 and the preceding species is in the character of the testes, the greater 

 anterior prolongation of the vitelline glands, and the range in size. In 

 this species adults with ova range from 1 mm. to 2.45 mm., while those 

 from Chlorichthys are all small, varying from 0.43 to 1 mm. in length. 

 The difference in size between the distomes from these two hosts is very- 

 marked. This leads to a decided difference in appearance. In the small 

 distomes the number of ova is very few, while the size of the ova remains 

 the same as in the larger distomes from Hcemulon. I do not feel justi- 

 fied at present in placing them in different species, but prefer rather to 

 regard the differences as due to the fact that they are living in hosts 

 which are not closely related. 



Variability of Testes. — Five of these small distomes were examined, 

 with the following result: (1) 1 testis, median; (2) no testis seen, (3) 

 1 testis, median; (4) 2 testes, 1 left, 1 right; (5) 1 testis, transverse, 

 faintly bilobed. The cells of the testes were loosely clustered as if the 

 organs were disintegrating. Ovary variously lobed. 



This species was found in the following hosts: 



Host, Hcemulon plumieri: 



1906, July 5, 6 fish, 7 distomes; July 15, 1 fish, 9 distomes; July 13, 

 2 fish, 1 distome. 



1907, June 28, 2 fish, few distomes; July 3 and 4, 16 fish, many 

 distomes; July 10, 12 fish, few distomes; July 13, 6 fish, few 

 distomes. 



1908, July 1, 7 fish, few distomes; July 14, 14 fish, few distomes. 

 Dimensions in life, flattened: Length 1.54, breadth 0.75; diameter 



of oral sucker 0.14, pharynx 0.07, ventral sucker 0.25 ; ova 0.048 by 0.027 

 excluding filament. 



Host, Hcemulon sciurus: 



1907, June 28, 1 fish, few distomes; July 12, 3 fish, 1 distome. 



Host, Chlorichthys bifasciatus: 



1907, July 1, 1 fish, 4 distomes; July 8, 1 fish, 2 distomes. 



Various shapes, linear to pyriform. Dimensions, life: Length 0.73, 

 breadth 0.23; diameter oral sucker 0.07, ventral sucker 0.14; ova 0.056 

 by 0.028. Another, length 1.15, breadth 0.45, pharynx 0.07, oral sucker 

 0.13, ventral sucker, 0.22; ova 0.054 by 0.027. 



Host, Iridio bivittatus: June 28, 1907, 6 fish, few distomes. 



These were small, pyriform with slender neck in some, oval when 

 compressed. Dimensions, life, flattened: Length 1.22, breadth 0.59, 

 oral sucker 0.11, pharynx 0.08, ventral sucker 0.28; ova 0.042 by 0.018; 

 length of filaments about 0.18. 



Host, Lachnolaimus maximus: July 18, 1906, 1 fish, 1 distome. 



