Helminth Fauna of the Dry Tortugas. 

 Dimensions of distomes mounted in balsam. 



45 



Host. 



From a nte°ri^r 

 Oral sk. Pharynx. Vent. sk. ^J™ 1 " Tnd'to' Length. Breadth. 



Epinephelus striatus. 

 Neomaenis griseus 



Do 



Ocyurus chrysurus. . . 



Do 



Xeomaenis analis 



Do 



Do 



0.44 



0.52 

 0.32 

 0.45 



o .60 

 1-37 

 1.47 

 I-I5 



0.80 



1 .06 

 o .60 



. 70 



1 . 20 



2.38 



2 .60 



I .90 



Host, Xeomcenis griseus: 



1906, July 5, 11 fish, 3 distomes; July 7, 4 fish, 1 distome; July 9, 



14 fish, 3 distomes; July 12,4 fish, few distomes. 

 1908, July 14, 4 fish, 1 distome. 



Host, Xeomanis analis: July 1, 1908, 1 fish, 3 distomes. 

 Host, Epinephelus striatus: July 4, 1907, 1 fish, 1 distome. 

 Host, Ocyurus chrysurus: 



1906, July 6, 3 fish, 1 distome. 



1907, July 11,3 fish, 1 distome. 



1908, July 3, 1 fish, 2 distomes; July 11, 1 fish, 1 distome; July 12, 

 3 fish, 1 distome; July 14, 1 fish, 1 distome. 



One specimen from this host had most of the spines still attached 

 to the circumoral region. There appeared to be 36 in the two circles. 



The length of the cirrus spines in a specimen from Epinephelus, in 

 life, was 0.01 mm. 



Stephanochasmus sentus sp. nov. (Figs. 84-86.) 



Body linear or slightly clavate, neck tapering, cylindrical, often 

 arched; mouth surrounded by a double row of spines, 18 in each row; 

 neck and anterior part of the body covered with spines which are evan- 

 escent. In some cases the neck was covered with globular tubercles, 

 in others the tubercles were flattened, in still others they were spines 

 of the usual low rounded type. All these conditions appear to be different 

 stages of shedding the spines, which seem to be evanescent, not only 

 those on the neck and body but also those around the mouth. The spines 

 do not, however, appear to be so readily lost as they are in Stephano- 

 chasmus casus. The oral sucker is variable ; the ventral sucker is usually 

 nearly circular in outline and 1.5 times the diameter of the oral sucker; 

 pharynx usually pyriform and much longer than broad, situated near the 

 ventral sucker and separated from the oral sucker by a long prepharynx. 

 There is an esophagus which may be as long as the pharynx, and' the 

 intestinal rami extend to the posterior end of the body. Genital aperture 

 median at anterior border of the ventral sucker; seminal vesicle behind 



