. Fossil Mollusca. 205 



and where the concentric striations cross these a cancellated 

 condition is set up ; margins crenulate ; ligamental furrow 

 excavated, oblique ; characters of lunule obscured by matrix ; no 

 dentition seen. 



Remarks. — The specimen refeiTed to this species shows extremely 

 well the chief characters of the shell. Both valves are in contact, 

 but not quite m situ : the left illustrates structural ornamentation ; 

 the right, represented by a cast, shows a posterior oblique ridge 

 and adductor scar, but no sinus or pallia! line are decipherable, 

 probably on account of youth, as the specimen is small and 

 apparently a young example. It is in a cream-coloured limestone. 



Dimensions. — Height 28, length 31, diameter 25 mm. 



Distrihution. — Species of wide distribution occurring in the Post- 

 Pliocene beds of the Clyde Basin, etc. ; in the Sicilian strata ; 

 and recent examples in the Mediterranean ; Canary Islands ; 

 America ; Indian Ocean (E. Romer) ; etc., etc. 



Locality. — Top of first inland cliff, about 300 feet above sea-level. 



Number on specimen : 1032. 



Examples : 1 . 



Venus, sp. 



A small block of cream-coloured limestone contains casts of 

 a right and left valve of this genus. The position of the muscle 

 marks and sinus, the characters of the posterior oblique area, and 

 the convexity of the valves, appear to show a relationship to Venus- 

 puerpera of Linnoeus, resembling, in fact, a figure called V. puerpera, 

 var., in Chenu's "Manuel Conchyliologie," 1862, vol. ii, p. 82, 

 tig. 352, although the absence of dental and sculptural characters 

 renders the specimen of doubtful specific value. 



Dimensions. — Height 55, length 65, depth of each valve 18 mm. 



Locality. — Top of first inland cliff, about 300 feet above sea-level. 



Number on specimen : 1032. 



Examples : Two valves on one slab. 



INDETERMINABLE SPECIMENS. 



A small mass of a rather coarse-grained yellowish-white limestone, 

 weathering a drab colour, largely composed of Lamellibranch shells, 

 which occur as casts having little or no characters sufficient for 

 identification. Some of the shells have a trigonal or nuculoid 

 appearance. 



Locality. — "West end of island, about 725 feet above sea-level. 



Number on specimen : 360. 



Examples: 1. 



