398 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 2 



Posttesticular space 0.270 to 0.390. Oral sucker 0.142 to 0.165 in diam- 

 eter; acetabulum 0.258 to 0.315 in diameter; sucker ratio almost 1:2 

 (about 4:7). Oral spines 40 (20 rows), possibly 38 in a few cases; all 

 spines approximately the same size, anterior row slightly larger, posterior 

 row extending beyond anterior row; largest spines 0.060 to 0.065 by 

 0.014 to 0.017; smallest spine 0.043 to 0.060 by 0.010 to 0.015. Pre- 

 pharynx long; pharynx pyriform, 0.210 to 0.240 long by 0.102 to 0.145 

 wide; esophagus very short; intestinal bifurcation just anterior to ace- 

 tabulum; uroproct probably present. Testes large, tandem, intercecal, 

 close together, almost alwaj^s in contact, rarely with a very few vitelline 

 follicles between them ; anterior testis globular or subglobular, almost as 

 wide as long; posterior testis longer than wide. Cirrus sac slightly sinuous, 

 extending about Ys the distance from acetabulum to ovary, never as far 

 as y2 ; cirrus very long, often protruded from genital pore ; genital atrium 

 opposite anterior half of acetabulum. Ovary ovoid, wider than long, 

 immediately anterior to anterior testis from which it is almost always 

 separated by a very few vitelline follicles. Vitellaria from base of cirrus 

 sac continuous to posterior end of body; dorsal, ventral, and lateral to 

 ceca but not covering the uterus; eggs 60 to 68 by 27 to 41 /x; metraterm 

 weak, usually so filled with eggs as to be invisible. 



Comparisons. This species is to be compared with those having com- 

 plete rows of oral spines and with the vitellaria ending at or near the 

 base of the cirrus sac. Of these, it is most like S. sentum (Linton) which 

 is common in related hosts at Tortugas, Florida. Only three differences 

 can be recognized : 5. anisotremi has 40 oral spines rather than 36 ; it has 

 a sucker ratio of 1 :2 (or nearly 2) rather than 1^; and the eggs are 

 somewhat smaller (up to 68 ju, rather than 75 to 85 fi or even more). 

 These differences are not great, but after studying specimens of S. sentum 

 from Florida, the writer believes they are sufficiently constant. S. cadu- 

 cum (Looss) has 48 oral spines, a sucker ratio of 1 :1, and (at least usu- 

 ally) interrupted vitellaria. S. minutum (Looss) has 36 spines and 

 smaller eggs. 



In comparing species of Stephanostomum, the writer can find no sig- 

 nificant differences between the descriptions of S. imparspine (Linton, 

 1905) n. comb, described from Beaufort, North Carolina, fishes and S. 

 sentum (Linton, 1910) from Tortugas, Florida. Linton doubtless was 

 dealing with more than one species in his records of "Dist. imparspine/' 

 one of which is probably identical with S. sentum. 



