26 Papers from the Marine Biological Laboratory at Tortugas. 



They are irregularly branching and unite behind the ventral sucker. 

 In general there are 2 main lateral branches, but with transverse con- 

 necting vessels in front of the ventral sucker and in the vicinity of the 

 pharynx, and are confluent in the head region. 



Host, Caretta caretta: June 29, 1907, 275 distomes, collected from 

 the intestine of one turtle. 



Some of the distomes were opaque white, thickish, and quiet; others 

 were translucent and very active. The larger of each kind about the same 

 size, 4 mm. in length. The smallest were without ova. One of the smaller, 

 quiet specimens measured 1.61 in length and 0.67 in breadth. The two 

 kinds do not differ much after they have been in alcohol. 



Dimensions of one of the larger, active specimens, flattened and 

 fixed over the flame: Length 3.8; breadth 1.6; oral sucker, length 0.56, 

 breadth 0.64; pharynx, length 0.33, breadth 0.28; ventral sucker 0.63; 

 ova 0.042 by 0.015. 



Dimensions of another taken from sections: Length 2.76; breadth 

 0.84; length of neck 1; oral sucker 0.50; pharynx, length 0.28, breadth 

 0.21 ; ventral sucker 0.50; ova 0.047 by 0.020. 



The ova in a small specimen, which was 1.54 in length, measured 

 0.030 by 0.015. 



Cymatocarpus undulatus Looss. (Figs. 15-22.) 



Zool. Jahrb., xn, pp. 593-594, Taf. 27, figs. 32, 33, 34. 



Body moderately thick, broadest in front of ventral sucker, some- 

 what narrowed posterior to ventral sucker; when flattened often spatu- 

 late. Color translucent white except in uterine portion, which in adult 

 individuals is characteristically colored by the eggs, the folds on the right 

 side being dark-brown and those on the left side lemon-yellow. The 

 body is covered with very dense, fine spines. Suckers about equal; 

 ventral sucker a little in front of the middle of the body; pharynx small, 

 adjacent to oral sucker ; esophagus long and slender ; intestinal rami short, 

 divergent, clavate, not reaching the ventral sucker. Genital aperture 

 near anterior border of ventral sucker. Copulatory apparatus large 

 and complex. The large cirrus-pouch curves around the left side of the 

 ventral sucker. At the base of the cirrus there are a number of small 

 bursse (about 4 small and 2 large) lined with fine spines. The cirrus 

 is peculiar and difficult to understand. Besides the base, already men- 

 tioned, there is a cylindrical portion with fine, short spines and compact 

 walls, i.e., its component muscle fibers not unusually coarse. Following 

 the cylindrical portion is a shorter, slightly enlarged portion with very 

 coarse, circular muscle fibers. Following this and between it and the 

 seminal vesicle there is a short, cylindrical portion with moderately 

 strong fibers. In this portion the circular and longitudinal fibers are 

 about the same size, giving the effect of a sieve or grating. Beyond this 

 is an oval sac, the seminal vesicle, constricted at its distal end and with 

 a strong wall which is continuous with the cirrus wall. The cirrus and 

 seminal vesicle are both surrounded by the cells of the prostate and all 

 are inclosed in the strong walls of the cirrus-pouch (figs. 15 and 16). 



