1 88 NEW YORK STATE MUSEUM 



Str. crebristriata, probably not attaining greater size or more pro- 

 gressed development in surface features than expressed in our specimens. 



Dimensions. Length, 13 mm; width on hinge, 16 mm. 



Locality. Grande Greve ; shore at Fruing's. 



Stropheodonta parva Hall protype avita nov. 



Plate 34, figures ig-21 



See Hall. Palaeontology of New York. 1859. 4; 85, pi. 11, fig. 5, 11 



Several brachial valves show at first the median groove and four to five 

 simple strong ribs on each side, such as characterize S. gal ate a, and 

 change this expression by the simple bifurcation of these ribs at about one 

 half their length and close upon the margin, by the subdivision of one or 

 the other of these branches. This is the character of S t r o p h. parva 

 Hall of the Schoharie grit of New York, a rare species, and comparison of 

 the Gaspe shell with the single exterior of the brachial valve figured or 

 known \op. cit., pi. 11, fig. 5] shows similarity of dimensions to be accom- 

 panied with the like character of surface. In S. parva the ribs are not 

 so strong and bifurcation begins sooner, that is, the period of simplicity con- 

 tinues longer in the Gaspe shell and hence gives it more primitive expres- 

 sion, in accordance with its antecedent date. These relations are shown by 

 the comparison of the two figures here given. 



Locality. Indian Cove, Gaspe. 



Stropheodonta galatea (Billings) 



Plate 35, figures 15-26 



Strophomena galatea Billings. Palaeozoic Fossils. 1874. v. 2, pt 1, p. 20, 

 fig- 9 



Original deseription. Shell of a medium size, semielliptical; cardinal angles about 

 90°; sides in the posterior half nearly straight and parallel; all of the exterior half uniformly 

 rounded. Ventral valve exceedingly convex; the cardinal angles compressed and slightly 

 recurved; umbo very prominent, narrowly rounded, projecting beyond the hinge line; beak 

 small, incurved; area moderately developed, strongly concave, especially under the beak and 

 for a short distance on each side thereof. Deltidium flat, triangular, smooth; its width at the 

 base about equal to the hight. When the surface of the area is perfect the dental striae 

 are only indistinctly or not at all visible, but where worn or exfoliated they come out to 

 view. They are slightly oblique, the convergence being from the dorsal edge of the area 

 inwards, or inclining towards the beak. The area in the lower, or dorsal, one third, lies 

 nearly in the plane of the lateral margin, but in the upper two thirds it is strongly 

 incurved, so as to become more nearly at a right angle to that plane. 



Dorsal valve deeply concave; nearly in contact with the ventral valve at the cardinal 

 angles, and for a space of about one fourth the width, all round the sides and front; the dis- 

 tance between the two valves being the greatest a little above the middle. Area of the 

 dorsal valve nearly as large as that of the ventral, parallel-sided, apparently not flat but 

 slightly convex. It seems to form an obtuse angle with the area of the ventral valve. 



Surface in one of the specimens covered with minute radiating striae, about 20 

 in the width of one line. Along with these there are others about twice or thrice their 



