162 PROCEEDINGS OF THE NATIONAL. MUSEUM vol.88 



UNCLASSIFIED FORMS 

 Genus PLEORCHIS Railliet, 1896 



PLEORCHIS AMERICANUS LUhe 



Plate 24, Figubes 32-i-330 



Distomiim polyorchis Stossich, Linton, Bull. U. S. Fish Coium. for 1899, pp. 



460, 461, figs. 363-365, 1901. 

 Pleorchis americanus Luhe, Rep. Pearl Oyster Fish. Gulf of Manaar, pt. 5, 



p. 103, 1906. 



Revised description of species: Of nearly the same breadth 

 throughout most of the length, tapering slightly from a point a little 

 back of the ventral sucker to the anterior end; posterior end more 

 or less truncate; body covered with fiat, round-pointed spines. 

 Oral and ventral suckers nearly equal; pharynx much smaller than 

 oral, from which it is separated by a prepharynx; prepharynx and 

 esophagus each longer than the oral sucker. The rami of the intes- 

 tines extend to the posterior end of the body, each sending off 

 numerous branches, which themselves may branch one or more times. 

 In the vicinity of the testes this branching is only on the lateral 

 sides, but behind the testes the branching is both lateral and medial ; 

 anteriorly each ramus is prolonged into a caecum which extends 

 forward beyond the level of the anterior end of the pharynx. The 

 genital pore is on the median line in front of the ventral sucker. 

 The cirrus is smooth; the cirrus-pouch lies dorsal to the right side 

 of the ventral sucker, encloses the seminal vesicle, which is in two 

 divisions, and extends well back of the ventral sucker. Testes 

 numerous, lying in two double rows, dorsal and ventral, on each 

 side of the median line for a distance approximating half the length 

 of the body. In the specimen of which the measurements are given 

 the distance from the anterior end to the first testis is 2.6 mm., from 

 the last testis to the posterior end, 1.1 mm., while the distance from 

 the anterior to the posterior testis inclusive is 3.7 mm. The ovary 

 is lobed, morulalike in horizontal section, and lies at the anterior 

 borders of the first testes, more of it on the right than on the left 

 side of the median line. The shell gland lies on the anterior border 

 of the ovary. Laurer's canal enters about on the median line dorsal 

 to the anterior border of the ovary. There is no seminal receptacle, 

 the early folds of the uterus acting in that capacity. The folds of 

 the uterus lie between the ovary and ventral sucker, passing on the 

 dorsal side of the ventral sucker to the genital pore. The vitellaria 

 fill the body behind the testes, and form broad lateral bands forward 

 to about the level of the posterior edge of the ventral sucker. The 

 main excretory vessel is single and on the median line. Ova rather 



