Helminth Fauna of the Dry Tortugas. 35 



vessel was seen. It was dark in color, extended from the posterior end, 

 and terminated abruptly in front of the cirrus-pouch. 



Dimensions of a specimen from Neomcenis griseus, life, flattened: 

 Length 4; breadth, anterior 0.37, middle 0.98, posterior 0.93 ; oral sucker, 

 length 0.22, breadth 0.26; pharynx, globular, 0.15; ventral sucker 0.33; 

 ova 0.078 by 0.051. 



Dimensions of a specimen with tiiangular outline and emarginate 

 posterior end, balsam: Length 2.30; breadth 0.94; neck 1.12; oral 

 sucker 0.24; pharynx 0.11 ; ventral sucker 0.34; ova 0.075 by 0.034. 



Another with similar outline but with the posterior end bluntly 

 rounded: Length 3.02; breadth 0.77; neck 1.50; oral sucker 0.22; 

 pharynx 0.08; ventral sucker 0.32; ova 0.075 by 0.034. 



In life the active specimens are flat and leaf-like, and greenish- 

 yellow, especially by transmitted light. The active specimens are elon- 

 gated and taper anteriorly. Others, not active, are thick, squarish, 

 opaque, and white. 



This species was found in the following hosts: 



Host, Neomcenis griseus: 



1906, July 5,11 fish, numerous distomes; July 7, 4 fish, 4 distomes, 

 length of one of largest 5.5 mm.; July 9, 14 fish, 27 distomes; 

 July 10, 4 fish, 4 distomes; July 16, 4 fish, 4 distomes. 



1907, July 7, 4 fish, numerous distomes; July 9, 5 fish, numerous 

 distomes. 



1908, July 1, 1 fish, 13 distomes; July 4, 1 fish, 50 distomes; July 12, 

 4 fish, few distomes; July 14, 4 fish, 9 distomes. 



Host, Neomamis apodus: 



1907, July 1, 2 fish, 1 distome, immature; July 3, 4 fish, 20 distomes, 

 mature and immature; July 9, 2 fish, 12 distomes, immature, 

 with conspicuous excretory vessel, dark-brown; July 11, 1 fish, 

 1 distome, immature. 



Host, Anisotremus virginicus: July 6, 1907, 1 fish, 1 distome. 



Host, Ocyurus chrysurus: July 10, 1907, 1 fish, 1 distome, immature. 



Host, Pomacanthus arcuatus: July 3, 1907, 1 fish, 1 distome, imma- 

 ture. 



Hamacreadium gulella gen. et sp. nov. (Fig. 55.) 



Here are described two distomes which were found with a lot of the 

 preceding species from Neomcenis griseus {Hamacreadium mutabile) 

 probably collected on July 4, 1908. They were not noticed to be dif- 

 ferent from the other species at the time of collecting. 



Body oval, the greatest diameter behind the ventral sucker and 

 tapering gradually to the anterior end; mouth subterminal; neck more 

 than one-third the entire length; ventral sucker more than 1.5 times the 

 diameter of the oral sucker ; pharynx separated from the oral sucker by a 

 short prepharynx; esophagus very short. The intestinal rami appear 

 to extend to the posterior end. Genital aperture in front of ventral 

 sucker, about half-way between it and the bifurcation of the intestines, 

 median (in one of the worms it is nearly as far forward as the bifurcation) . 

 The cirrus-pouch inclosed the scanty prostate cells and the seminal ves- 



