Nelson on Tertiary Mollusca of Peru. 201 



Tellina, sp. ind., A. 



I refer to this genus a badly broken specimen, having the general 

 forra of a Tellina^ though no characters remain for its determination. 

 If perfect, our specimen would have about the following measure- 

 ments : length 33 millim. ; breadth 55 millim. 



Tellina, sp. ind., B. 



A specimen, of which it is impossible to see the hinge, I also refer 

 to this genus. It is proportionally broader than the last species. 

 Surface marked by fine, nearly equal, flat stria?. Length 8*8 millim. ; 

 breadth 15 "40 millim. ; height 3 "4 millim. 



Mactra Zorritensis, sp. nov. 



At least two species of Mactra are found in this collection. The 

 shell of the first is ventricose. Umbos convex, prominent, incur- 

 ved. Anterior mai'gin long, sloping; posterior margin strongly 

 angulated with the lateral margin, and depressed. Hinge line nearly 

 straight ; fossette impressed and triangular ; cardinals divergent, 

 forming a prominent V; laterals very large, well developed. Length 

 16-1 millim. ; breadth 21 millim.; height 11*06 millim. 



Mactra, sp. ind. 



This species may be told from the preceding, which it very much 

 resembles, in being broader, having less prominent umbos ; and 

 being less convex; posterior margin not so angulated. Length 12 

 millim. ; breadth 18-2 millim. ; height V'O millim. 



? Harvella, sp. ind. 



I refer to this genus, doubtfully, some large specimens, which are 

 mostly casts. From lack of specific characters it is impossible to 

 settle the relations definitely. Our best specimen shows the umbos 

 convex and impressed; ligament area very deep; surface of shell 

 marked by strong concentric ribs. 



Dosinia grandis, sp. nov. 



Shell large, solid, sub-equilateral ; length and breadth nearly 

 equal; broadest just above the middle line. Beaks elevated, nearly 

 central, curved inward and forward. Lunule heart-shaped, very 

 deeply impressed, two-thirds as wide as long, marked by striations? 

 which become finer as they pass into it. Anterior end short. An- 

 terior and posterior ends nearly equally rounded. Ligament large ; 

 scar long, striated longitudinally. Surface covered by a thick epider- 



