Helm iii tli Fauna of the Dry Tortugas. 



43 



Comparative measurements, specimens in balsam: 



[Nos. i and 2 from Epinephelus, No. 3 from Mycteroperca.] 



Host, Epinephelus striatus: July 7, 1906, 3 fish, 2 distomes. 



Host, Epinephelus morio: June 29, 1908, 1 fish, 2 distomes. 



Host, Mycteroperca venenosa: July 16, 1907, 1 fish, 1 distome. 



In this specimen small tube-like structures were noted in the walls 

 of the head and neck like those in Siphodera vinaledwardsii. Length 

 of this specimen in balsam is 2.28, length of neck, 1.02. 



Distomum sp. 



Immature, encysted in flesh. 



These distomes were encysted in the flesh above the backbone, near 

 the dorsal spines, about midwav between the abdominal cavity and 

 base of caudal fin. Diameter of cyst 1.35 mm. There is a general resem- 

 blance to the form which I have recorded in reports on the Woods Hole 

 and Beaufort regions under the name Distomum valdeinflatum Stoss 

 The worms could be seen plainly through walls of the cysts. Dimensions, 

 flattened: Diameter of anterior sucker 0.20; ventral sucker 0.28; diam- 

 eter of body, in front of caudal enlargement 0.30, of caudal portion 1.75. 



Host, Calamus calamus: June 29, 1890, 2 fish were examined and 

 2 cysts found in one of them. 



Mesolecitha linearis gen. et sp. nov. (Figs. 170-172.) 

 Etymology: piaov, middle; liKtdos. yolk. 



The body linear, bluntly rounded at both ends, smooth under low 

 magnification, but when highly magnified minutely or prickly spinose 

 on the margins, cylindrical; mouth subterminal; oral sucker larger than 

 ventral; pharynx adjacent to oral sucker; esophagus short; rami of 

 intestines thick-walled and reaching nearly to the posterior end of the 

 body: ventral sucker at about the anterior fourth. Genital apertuie at 

 the anterior border of the ventral sucker; cirrus short, stout, and armed 

 with short spines: prostate conspicuous, dorsal to the ventral sucker 

 and extending beyond its caudal border; seminal vesicle oval, strong- 

 walled, at base of prostate; testes 2, close together, one behind the other 

 and situated a little nearer the ventral sucker than the posterior end. 

 Ovary oval elliptical, a short distance behind the central sucker on 

 ventral side of body; shell-gland on right antero-dorsal side of ovary. 

 To the right of the ovary and shell-gland and extending caudad is a 

 convoluted tube, a portion of the titerus, which appears to represent the 

 seminal receptacle with ova lying in the midst of the spermatozoa which 

 fill the tube. Folds of the uterus lie between the testes and the ventral 



