TREMATODES FROM FISHES — LINTON 7 



across in my study of the food and internal parasites of fishes were 

 turned over to him. Following are notes on tristomes from the gills 

 of the swordfish (Xiphias gladius), collected on July 15, 1904, and 

 July 13, 1911 (U.S.N.M. No. 8150). On the former date three tris- 

 tomes were collected from the gills of one swordfish; on the latter 

 date two swordfish were examined and 75 tristomes obtained from 

 the gills of one; none was found on the other. Those of the first 

 lot were yellowish, transparent, leaflike, and from 7 to 12 mm. or 

 more in diameter. In the second lot they were pinkish to blood-red, 

 becoming pale when much extended. Some of them, which soon 

 became inactive, were blood-red with a white border. This mar- 

 ginal border bore clusters of small spines of various shapes (pi. 14, 

 fig. 172). After lying overnight in sea water most of the worms, 

 which had been active on the evening before, were still active. Wlien 

 the table was slightly jarred, the more active worms would con- 

 tract quickly. The largest, when expanded, were 20 mm. or more in 

 length and 15 mm. or more in breadth. They were then very thin, 

 leaflike, transparent, yellowish white. When touched they con- 

 tracted quickly, the length being much lessened, but the breadth 

 remaining about the same. Upon repeated irritation they would 

 become nearly circular in outline, the color in the contracted state 

 being deep pink. Eggs dark brown, tetragonal, with a filament at 

 each of the four trihedral angles, one filament being longer than 

 the others; diameter, excluding filaments, 0.1 mm. 



In a lot of 93 tristomes, all but two belong to this species. These 

 vary greatly in size and shape. Of 31 specimens mounted in balsam, 

 25 are longer than broad, 4 are broader than long, and 2 have the 

 length and breadth equal. Smallest, length, 4 mm., breadth, 2 mm. ; 

 largest, length, 13 mm., breadth, 9 mm. In 20 specimens, average 

 length, 8.6 mm., breadth, 7.2 mm., the average number of groups of 

 spines on one lateral margin was 45.6; maximum 51, minimum 40. 

 There are two small, slender, slightly arcuate spines on the posterior 

 sucker. These spines were 0.12 mm. in length and 0.02 mm. in 

 breadth, on a specimen 5 mm. in length and 6 mm. in breadth, and on 

 another 12 mm. in length and 10 mm. in breadth. In most cases 

 these spines were situated in front of the posterior central loculus, 

 but in four cases they were observed to be in front of the left posterior 

 loculus, and in one at the central end of the right lateral loculus. 

 The posterior dorsal surface of these worms is papillate; also, in 

 strongly contracted specimens, the posterior margin is more or less 

 incised behind the pedicel of the posterior sucker. Specimens which 

 have been flattened under pressure during fixation have the posterior 

 margin entire, or but slightly emarginate. The pharynx is usually 

 broader than long. In 24 specimens examined, 3 were found in 



