260 CHITONID.E. 



Chiton marginatus, Pexnant, Brit. Zool. iv. 61, t. 36, fig. 2. — Lin.; Gmelin, Syst. 



3206, No. 26. — Moxtagu, Test. Brit. 1. — Pulteney, Dorset Catal. 25, pi. I, fig. 



2. — Matox and Rackett, Lin. Trans, viii. 21, pi. 1, fig. 2. — Wood, Gen. Conch. 



21, pi. 3, fig. 4. — ScHROET. Einl. in Conch, iii. 508. — D'Argenv. Conchyl. t. 25, 



fig. M. — Lam. An. sans Vert. vii. 492. — Sowerby, Conch, lllust. figs. 106-112. 



— Fleming, Edin. Encyc. vi. 102; Brit. Anim. 2S9. — Gould, Inv. 147, fig. 22. 

 Chiton cinereits, Lin. Syst. Nat. 12th cd. p. 1107. — Lowe, Zool. Journ. ii. 99, pi. 5, fig. 



5. — Forbes and Hanley, Brit. Moll. ii. 402. — Stimpson, Check Lists, 4 (1860). 



Shell small, ovate, moderately convex, with an elevated ridge 

 along the centre, where each of the valves projects backwards in a 

 minute beak, ending at the centre of the posterior valve ; valves 

 faintly divided into triangles; surface otherwise apparently smooth, 

 but under the magnifier it is fjund to be beautifully shagrcened, the 

 granules behig arranged in diamonds on every part. Color a dead, 

 dull ashen or greenish color, sometimes mottled. Margin narrow, 

 membranous, coated with a dusty pigment, which is alternately 

 hoary and brownish. Length, half an inch ; breadth, three tenths 

 of an inch. 



A single specimen of this shell was found living, a few years 

 since, by Dr. Charles Pickering, at Philli})s's Beach, and is now in 

 the Cabinet of the Academy of Natural Sciences at Philadelphia. 

 It is a common British species. 



It is an inelegant shell at first sight, its dingy, dull surface pre- 

 senting nothing attractive. But no one can fail to admire its beau- 

 tiful sculpture when viewed under the magnifier. The serrated, 

 reflected margin usually mentioned in descriptions, is merely a con- 

 traction of the margin about the ends of the valves, such as we see 

 in many other species. 



It is allied to C. apicidatns ; but we find the lateral triangles as 

 much sculptured as the dorsal in this ; the dots are diamond-shaped, 

 and arranged in quincunx, and not bead-like, and arranged in series. 

 From our other species it is distinguished by its dead surface. 



Chiton ruber. 



Fig. 24. 



Shell small, oval, elevated, cariiiated; valves marked bylines of growth; other- 

 wise smooth, strongly beaked ; margin pulverulent, red and white. 



Chiton ruhcr,l.c\yv., Zool. Jonrn. ii. 101, ])1. 5, fig. 2. — Sowerby, Conch. Illnst. figs. 

 103, 104, lower fig. — Fleming, Edin. Encyc. vi. 102 ; Brit. Anini. 289. —Dk Kay, 

 N. Y. Moll. 165. — Stimpson, Check Lists', 4 (1860). 



