232 THE ROYAL SOCIETY OF CANADA 



OLIGOTREMA Bourne 



Oral aperture with six branched muscular lobes. 



Pharynx without proper folds. No infundibula. Stigmata 

 relatively few, short and more or less curved. Dorsal lamina absent. 

 Dorsal tubercle a simple slit. 



A gonad on each side, the left above the intestinal loop. Testi- 

 cular lobes grouped at blind end of ovary, with a single vas deferens, 

 not accompanying ovary and oviduct. 



Type and single species — 0. psammites Bourne. 



HEXACROBYLUS Sluiter 



Oral aperture with six large branched muscular lobes. 



Pharynx without folds. Dorsal lamina with smooth margin. 

 Dorsal tubercle a simple opening. Tentacles simple or absent. 



A gonad on each side, the left above the intestinal loop. Testi- 

 cular lobes grouped at blind end of ovary, with a single vas deferens, 

 not accompanying ovary and oviduct. 



Type species — H. psammatodes Sluiter. 



The only other species of the genus is H. indiens Oka (1913, p. 6). 



GAMASTER Pizon 



Pharynx with seven longitudinal bars on each side in place of 

 folds. Infundibula in rows corresponding to the bars, each consisting 

 of one or two long spirally coiled stigmata. Condition of dorsal 

 lamina and dorsal tubercle not known. 



A single gonad, situated on the right side. Testicular lobes 

 arranged radially at blind end of ovary. Vas deferens (or vasa 

 deferentia?) not accompanying ovary and oviduct. 



Type species — G. dakarensis (Pizon). 



The only other species is G. woermanni (Michaelsen), described 

 by Michaelsen in 1914 (p. 423) as Eugyra w. Its affinities are, how- 

 ever, definitely with Pizon's species. Gamaster parallels the typical 

 Eugyrinae both in the condition of the stigmata and in the failure of 

 the pharyngeal folds to develop. 



Uncertain Genera 



Hartmeyer (1914, p. 8 ) has formed the genus Molgulina for those 

 species, formerly assigned to the genus Molgula or Caesira, which 

 have a small number of longitudinal bars on each fold and the infundi- 



