TREMATODES FROM FISHES — LINTON 



55 



Vitellaria dense, filling posterior part of body to within 1.9 mm. of 

 ventral sucker. Distance from anterior end to ventral sucker 0.84 

 mm. Length of prepharynx about 0.32 mm. 



STEPHANOSTOMUM TENUE (Linton) 



Plate 4, Figures 32-34 



Distonmm tenue Linton, Proc. U. S. Nat. Mus., vol. 20, pp. 535, 536, pi. 52, 



figs. 2-8, 1898; Bull. U. S. Fish Comm. for 1899, pp. 455, 456, 468, 469, 



1901. 

 Distomum tenue tenuissime Linton, Proc. U. S. Nat. Mus., vol. 20, pp. 536, 



537, pi. 52, figs. 9-12, 1898. 

 Distomes referred to this species from 10 species of fishes in the Beaufort, 



N. C, region, Bull. U. S. Bur. Fish., vol. 24, 1905. 



Many of the distomes here recorded are imperfect in that the oral 

 spines are either missing or in such condition that their exact number 

 can not be determined; in many cases also the dermal spines are 

 evanescent. About 42 oral spines were counted in distomes from 

 Roccus saxatilis and Morone americana and about 48 in distomes from 

 Hemitri'pterus americanus. 



In general the ova of the distomes recorded under S. tenue measure 

 0.08 by 0.04 mm. or more, while those under S. dentatuTn are 0.06 by 

 0.03 mm. or less; all measurements were made on material mounted 

 in balsam. The average diameters of oral sucker, pharynx, and ven- 

 tral sucker of distomes from different hosts are as follows : 



Hosts. — Sand launce {Ammodytes americanus)^ sea raven {Hemi- 

 tripterus americanus), kingfish {Mentlcirrhus saxatilis), white perch 

 {Morone americana), striped bass {Roccus saxatilis), toadfish {Op- 

 sanus tau). 



Record of collections. — One (U.S.N.M. No. 8205), collected Octo- 

 ber 20, 1914, from sand launce. Measurements in balsam : Length, 

 3 mm. ; breadth, 0.75 mm. ; oral sucker, length, 0.17 mm., breadth, 0.22 

 mm.; pharynx, length, 0.32 mm., breadth, 0.28 mm.; ventral sucker, 

 length, 0.35 mm., breadth, 0.35 mm. ; ova, 0.096 by 0.054 mm. Most 

 of the oral spines are missing, coarse spines on neck; prepharynx at 

 least as long as pharynx; esophagus very short; seminal vesicle 

 extends for three-fourths the distance from ventral sucker to ovary. 

 There is a short interval between the testes in which a few vitelline 

 follicles lie; ovary at anterior edge of testis; shell gland at anterior 



