28 Papers from the Marine Biological Laboratory at Tortugas. 



and were somewhat flaccid were measured after they had been flattened 

 under the cover-glass. The longest were 5.5 mm. in length and 2 mm. 

 in breadth; the smallest 2 by 1 mm. More detailed dimensions of the 

 larger specimen are: Length 5.5, breadth 2; breadth, through anterior 

 sucker 1, between suckers 1.8, at ventral sucker 1.5, between ventral 

 sucker and posterior end 1.4, near posterior end 0.7; oral sucker, length 

 0.28, breadth 0.30; pharynx 0.11; ventral sucker 0.28; distance from 

 oral sucker to forks of intestine 1.9; length of rami of intestine 0.7; 

 greatest breadth of intestine 0.25; ova 0.024 by 0.012. 



Orchidasma amphiorchis (Braun) Looss. (Figs. 23-28.) 



Braun, Mitt. a. d. Zool. Mus. Berlin, Bd. 11, 1901, p. 20, Taf. 1, figs. 7, 11. 

 Looss, Centralbl. f. Bak., Par. u. Infek., Bd., xxx, 1901, p. 560; Zool. Jahrb., 

 xvi, 1902, pp. 500, 502. 



Body of various shapes, but prevailingly linear, sometimes vase- 

 shape, usually rounded in front and slightly contracted back of the head, 

 posterior end narrowing to a blunt point, anterior end densely covered 

 with short spines. Oral sucker about twice the diameter of the rather 

 weak ventral sucker ; pharynx a little less than half the diameter of the oral 

 sucker, its length about equaling its breadth. There is a short prepharynx 

 and an esophagus about equal in length to the pharynx. Intestinal rami 

 with rather thick walls and extending to the posterior end of the body. 

 Genital aperture on median line at anterior edge of ventral sucker. 

 Cirrus-pouch very long, the retracted cirrus lying in convoluted folds 

 behind the ventral sucker. It is thickly beset with relatively large spines. 

 Testes 2, small, subglobular, remote from each other, with folds of the 

 uterus between them. One testis is near the posterior end of the body, 

 the other a little behind the middle. Seminal vesicle inclosed in cirrus- 

 pouch at its distal end. Cirrus surrounded by prostatic cells. Ovary 

 small, lying close to antero-dorsal surface of anterior testis. In most 

 cases it can be seen only in dorsal view. Seminal receptacle dorsal to 

 anterior testis and protruding beyond its right anterior edge. Shell- 

 gland on medial side of seminal receptacle. Vitelline glands marginal, 

 extending from anterior testis, or a little in front of it, to the anterior edge 

 of the ventral sucker or not quite so far, made up of small, subglobular 

 bodies. The folds of the uterus lie between the testes and in front of the 

 anterior testis. The uterus ends in a capacious, muscular metraterm, 

 which, like the cirrus, is lined with relatively large spines. These spines 

 are larger at the distal end than they are near the genital aperture. The 

 spines in both cirrus and metraterm have basal supports. Ova small, 

 short-oval or circular in outline, with thick shells. 



In some of the mounted specimens there were numerous, dark- 

 colored, slender, bristle-like structures in the lumen of both the cirrus 

 and metraterm. 



Dimensions in balsam. 



Length 



Breadth 



Oral sucker. . . . 

 Ventral sucker 

 Pharynx 



2-31 

 0.63 

 °-33 

 o . 16 



0.13 



.66 

 .45 

 •32 

 .16 



1.42 

 0.58 

 0.25 

 o. 16 

 o . 11 



