362 



G-eims PHOLADOMYA, Sowerby. 

 Pholadomya subelong-ata. Meek. 



Plate 2, figs. 1 aiid la. 

 Pholadomya suhelongata, Meek (1857), Trans. Albany Institute, iv, i'2. 



Shell transversely oblong-oval, rather elongated and depressed; valves 

 gibbous, particularly in the umbonal region ; anterior side very short 

 and abruptly rounded ; posterior side rounded or subtruncated, and 

 more or less gaping; basal margin forming a broad semi-elliptical 

 curve, sometimes nearly straight along the middle ; dorsal margin con- 

 cave in outline, so as to be nearly parallel with the base ; false area 

 rather well defined just behind the beaks, but becoming obsolete a 

 little further back ; beaks nearly terminal, depressed, and incurved. 

 Surface of each valve ornamented by from sixteen to twenty-five small 

 radiating costfe, most of which pass from the beaks obliquely backward 

 and downward to the postero-basal margin, those near the anterior end 

 being much more distant than the others, and separated by spaces from 

 four to six times their own breadth. Small concentric wrinkles mark 

 the surface in the other direction, giving the costse a slightly crenulated 

 or subnodose appearance. 



Length, 1.60 inches : height (at the beaks), 0.75 inch ; breadth or 

 convexity, 0.69 inch. 



In form, this species resembles somewhat varieties of Pholadomya 

 foliacea, Agassiz (Etud. Grit, sur les Moll., p. 102, pi. 7, particularly fig. 

 8), but its beaks are not near so oblique, and located farther back. Its 

 costse are also smaller and more defined as well as more numerous, while 

 its dorsal outline is more concave. 



Locality and position. — ISTanaimo, Vancouver's Island, also on 'New 

 Castle Island ; Cretaceous. 



Genus GONIOMYA, Agassiz. 

 GoNiOMYA BOREALis, Meek. 



Plate 2, fig. 2. 



Fholadomya (Goniomya) horealis. Meek (1857), Trans. Albany lust., iv, 41. 



Shell transversely subovate or oblong-ovate, moderately compressed ; 

 anterior side rather abruptly rounded ; posterior extremity truncated ; 

 cardinal margin sloping from the beaks, the anterior slope being more 

 abrupt than the other ; base forming a broad gentle curve, rounding up 

 more gradually in front than behind ; beaks moderately prominent, 

 and located about half-way between the middle and the anterior end. 

 Surface ornamented by from twenty to twenty-five small costse, which 

 pass down the sides of the shell from the dorsal margin behind and in 

 front of the beaks, so as to meet at acute angles along an imaginary 

 line extending from each beak obliquely backward and downward to 

 near the middle of the base. A few of those near the posterior and 

 anterior ends reach the base before uniting to form an angle. Obscure 

 lines of growth are also seen on portions of the surface. 



Length about 1.70 inches ; height, 1.12 inches ; breadth, 0.65 inch. 

 The only specimen of this species in the collection is imperfect, being 

 somewhat distorted by pressure, and broken at the extremities. The 



