Nelson on Tertiary Mollusca of Peru. 205 



posterior muscular scar. From Area tuberculosa it may be distin- 

 guished by its very broad muscular scar. 



I take pleasure in dedicating this species to Mr. E. P. Larkin, to 

 whom, and Prof. F. H. Bradley, the collection is due. 



Scapharca, sp. ind. 



A single specimen I refer to this genus, although its true relationship 

 can not be made out, as it is impossible to see the hinge line. In ex- 

 ternal characters it resembles S. nux Sby., and might at first glance, 

 be confounded with that species. The shell is less elongated ; ribs 

 broader and the spaces between the ribs narrower than in S. mix. 



Length 15'2 millim.; breadth 17*2 millim.; height 11*85 millim. 



Leda acuminata, sp. nov. 



Plate VII, figure 8. 

 Shell oblong. Anterior margin slightly produced, but rounded ; 

 posterior produced and acuminate. Umbos prominent, very convex 

 above, incurved below. Surface marked by broad, flat ribs, sepa- 

 rated by narrow, but well marked spaces. Hinge line slightly curved ; 

 teeth numerous and subequal. Shell slightly depressed posteriorly, 

 forming indistinct angulations with the lateral margins. Three speci- 

 mens measure as follows : 



Length, 6-2 millim. Breadth, 11-6 millim. Height, mUlim. 



" 10-8 " '• 20'0 " " 8-2 " 



14:-2 '-■ " 25-1 " " 11-8 " 



This fine species is quite abundant and may be easily recognized by 

 its great convexity, especially in all mature specimens ; by its flattened 

 striations, and regular teeth. 



Pecten, sp. ind. 



Two species are represented by single valves. First valve has 14 

 broad, flattened ribs, averaging 3 millim. in width at the lower mar- 

 gin, crossed l)y fine concentric lining. 



Second valve is very convex ; marked by 20 strong, rather acute 

 ribs ; spaces between them narrow. Whole surface marked by strong 

 concentric lines. 



First, Length, 41-4 mi lira. Breadth, 44'1 millim. 



Second, " 39-2 " " 39-6 " 



Ostrea, sp. ind., A. 



A badly worn valve of this genus is remarkable for its great 

 weight, 5 lbs. 6 oz., and when perfect must have weighed over 6 lbs. 



