82 THE ROYAL SOCIETY OF CANADA 



Pelecypoda. 



Genus — Goniomya. 



Goniomya uniangulata, cf. G. americana (Meek)/-' 



(Plate III, Fig. 1) 



This species is represented by three very imperfect specimens, the 

 largest of which appears to have been about 25 mm. in length by 17 mm. 

 in height. The costae converge along the flanks without horizontal 

 cross bars, and are well shewn, but the concentric lines of growth in the 

 best preserved specimen are only faintly suggested, while the bead-like 

 granules described by Meek in G. americana were not seen. 



Goniomya transversicostata (sp. nov.), cf. G. duboisi. 



(Plate III, Fig. 2) 



Of this species there is only a fragment comprising the umbonal 

 part of a left valve. The converging costse are united by horizontal 

 crossbars toward the beak, but toward the ventral margin they continue 

 until they meet, without a crossbar, at an angle of about 32°. A line 

 drawn from the beaks through the points of convergence of the costae, 

 or bisecting the crossbars, would be inclined backwards from the 

 vertical about 10° or 15°. A well-marked escutcheon is present, and 

 a ridge extends backwards from the beak just below the cardinal 

 margin, from which it diverges slightly, leaving an area between itself 

 and the edge of the escutcheon. The costae of the posterior part of the 

 shell cross this ridge, but fade out before reaching the escutcheon. 

 Concentric lines of growth can be clearly seen with a lens as fine sharp 

 ridges crossing the costae, and the gi-anular surface discribed by Meek 

 in G. americana appears also to characterize this species. 



Genus — Trigonia . 

 Sub-genus Scabra) (Agassiz). 



Trigonia flexicostata (sp. nov.) cf. T. scarburghensis \ 



(Plate III, Fig. 3) 



The material on which this species is based consists of two casts, 

 both of the interior of left valves. The total length from front to rear 

 is 65 mm., the maximum depth from beak to ventral margin, 42 mm. 

 The beak is prominent and distant from the anterior end from a fourth 



*U. S. G. S. Ter. 



tPalaeontographical Soc, Vol. 20, British Trigonia. 



