364- VENERIUM. 



young : beaks small, slightly turned towards the anterior side, 

 and nearly contiguous ; umbonal area prominent : lunule lan- 

 ceolate, rather deep, but rarely denned by a separating groove : 

 ligament long, yellowish-brown or horncolour, projecting be- 

 yond the dorsal margin, and conspicuous from the contrast of 

 its colour with that of the shell : hinge-Une obtuse-angled in 

 the adult, and rectangular in the young: hinge-plate solid: 

 teeth, in the right valve three cardinals ; the middle one short, 

 thick, triangular, and double, crowned with jagged edges or 

 points ; the other two laminar, and equally diverging from 

 the central tooth, the anterior being much the longest of all ; 

 the left valve has only two cardinals, representing the letter 

 V reversed, the posterior being double, and the other erect and 

 laminar ; the intermediate space receives the central tooth of 

 the right valve ; the anterior tooth in each valve is elongated 

 or continued in the form of an oblique ridge, which has the 

 appearance of a lateral tooth : inside chalky-white ; margin 

 smooth and bevelled towards the edges : pallia! scar broad, 

 removed far from the margin ; sinus very large, extending to 

 within one-third of the diameter in the direction of the beaks : 

 muscular scars strongly marked, the anterior much longer 

 than the other, which is oval. L. 1*25. B. 1-35. 



Var. 1. ventrosa. Shell smaller and more ventricose. 



Var. 2. oequalis. Shell equilateral, compressed in front : 

 heals more prominent and central. 



Habitat : Fine and muddy sand, in all our bays 

 and within the line of soundings, at from 3 to 100 

 fathoms. It is fossil at Belfast, " in vast numbers and 

 very large " (Hyndman and Grainger) ; Ayr (Smith) ; 

 Kyles of Bute (Crosskey). Var. 1. Arran I., co.Galway 

 (Barlee) ; Shetland (J. G. J.) . Var. 2. Scilly Isles (Lord 

 Vernon); Bantry Bay (Humphreys); West coast of 

 Scotland (Barlee). This species is distributed from the 

 Loffoden Isles (Sars) to Mogador (R. T. Lowe) and the 

 iEgean (Forbes). South-Italian tertiaries (Philippi). 



The animal is sluggish. The tubes of individuals 

 which I examined were very short, although not united. 

 Mr. Clark says that " the siphonal apparatus has the 



