ANOMIA. 35 



narrow, fixed in a cavity beneath the hinge: hinge-line 

 slightly curved : hinge-plate thick but narrow : orifice rather 

 large, much broader below than above ; outer edge not re- 

 flected : inside bluish-green, highly iridescent, furnished in the 

 lower valve with a ledge to receive the cartilage : muscular 

 scar large, showing in the upper valve the impression of two 

 inner portions of the muscle of a roundish-oval shape and 

 often confluent, the larger one of which is placed in the middle, 

 and the smaller one a little below it on the left-hand side ; in 

 the lower valve there is only one impression, placed as in the 

 last species: plug pear-shaped, thin, and coarsely striate 

 lengthwise. L. 1-3. B. 1-45. 



Var. striata. Shell sometimes nearly convex, covered with 

 numerous and fine longitudinal striae, which often rise into 

 minute scales, becoming prickly and occasionally decussated by 

 the transverse lines of growth ; coloured rays more distinct 

 and somewhat wavy. A. striata, Loven, Ind. Moll. Scand. 

 p. 29. F. & H. ii. p. 336, pi. Iv. f. 1, 6, and pi. liii. f. 6. 



HABITAT : 10-86 fathoms, on hard ground and shell- 

 banks everywhere, usually concealed in the hollows of 

 old bivalves. It is, however, not so common as the last 

 species, although equally diffused ; and they are found 

 together. The variety occurs in Shetland and on the 

 west coast of Scotland. A. patelliformis is a tertiary 

 fossil of the Clyde beds, and of the Red and Coralline 

 Crag, as well as of the newer deposits of Italy and Sicily, 

 and also of the Uddevalla shell-bed. Abroad this species 

 ranges from Scandinavia to the Mediterranean. Ac- 

 cording to Chierighini it inhabits the Adriatic ; Wein- 

 kauff has included it in his list of Algerian shells under 

 the name of A.pectiniformis, Philippi; the variety, as 

 well as the ordinary form, have been taken by M. Martin 

 in the Gulf of Lyons; Middendorff has recorded it 

 from Sitka Sound, and Dr. Philip Carpenter from the 

 North-west coast of America. 



It differs from A. ephippium in its more regular out- 

 line, thinner texture, coloured streaks, peculiar sculp- 



