LIST OF PLATES. 3 



Fig. 4. Lophyrus articulatus, Sby. : a, front profile of a specimen abnormally tri- 

 lobed ; the dotted line shows the same profile of an elevated specimen ; 

 b, terminal valves of two specimens, one with inner margin incurved, the 

 other excurved ; c, medial valves of two specimens, one much waved, the 

 other nearly straight. These characters are much dwelt on by Midden- 

 dorff in the discrimination of species. 



Fig. 5. A monstrosity of Fissurella virescens, Sby., inside view, with a circular hole 

 in addition to the normal one. 



PLATE IX. 



Fig. 1. Crucibulum imbricatum, Sby., Brod., Desh. =Patella scutellata, Wood,= 

 Calypeopsis rugosa, Less, non Desh. : including the non-pitted form, Dy s- 

 potcea dentata, Mke.=Calyptrcea ? extinctorium, Sby. non Lam.= Ca- 

 lyptrcea rugosa, Val., Rve., non Desh. : showing development, a, fry, 

 magnified, outside view ; b, ditto, inside, shell like Narica, with umbilical 

 chink, slight columellar lip, and a thin film of patelliform margin sur- 

 rounding the whole; c, young state, slightly magnified, cup much ex- 

 panded; in this state it appears to belong to the subgenus Dispotcea (Say) 

 of H. & A. Ad.; d, ditto, outside view, ribs scarcely indicated; e, 

 adolescent, ribs strongly developed, cup-angle narrower ; /, a stage nearer 

 maturity, cup-margins nearly closed ; g, adult state. 



Fig. 2. Crepidula Idorsata, Brod., var. bilobata, nearly adult (Crepipatella dorsata, 

 H. & A. Ad.), to compare wither. 1 c and 3 a. 



Fig. 3. Crucibulum spinosum, Sby. ,=Patella Peziza, Wood,= Calyptrcea tubifera, 

 Less.,= Calypeopsis auriculata, D'Orb. non Chemn. ; including Calypeop- 

 sis tenuis, C. hispida, and C. maculata, Brod. The C. quiriquina, Less.= 

 C. Byronensis, Gray, MS.= C rugosa, D'Orb. (pars), is probably a coarse 

 variety of the same species ; and the C. rugosa, Desh., non Less, nee Val. 

 = C lignaria, Brod., may be a distorted growth of the same variety. 

 a, young state, magnified ; b, the same, a stage older, wrinkles developed 

 crenating the margin, shape abnormal ; c, inside of smooth form, adult ; 



d, a specimen with the cup diseased, probably owing to the decay of half 

 the outside, where the commencement of the cup may be seen exposed ; 

 margin of the undecayed part thick and in layers, as in C. quiriquina ; 



e, outside view of specimen without spines, wrinkles very faint ; /, speci- 

 men with a very few rudimentary spines in the form of tubercles, and 

 faint, curved, radiating lines indicating the direction in which the spines 

 would normally appear ; g, another specimen, smooth over most of the 

 surface, but with spines fully developed at the top ; h, a specimen with 

 wrinkles almost evanescent, yet with a few well-developed spines, in 

 straight radiating lines ; i, a specimen of normal development, with 

 irregular wrinkles crossed by curved rows of spines ; j, portion of internal 

 margin of specimen h ; k, margin of specimen with spines partly formed, 

 open ; I, ditto fully developed, hollow throughout ; m, profile of specimen 

 beginning with regular margin, smooth, afterwards with irregular margin 

 and a few long spines at one corner; n, profile of smooth specimen 

 beginning regularly, then with different amounts of irregularity, ending 

 with a regular margin ; o, three specimens in profile, laid for the vertex to 

 coincide ; the first is flattened throughout, forming a regular, obtuse- 

 angled triangle ; the second (shaded) begins very conical, spinous, then 

 with two stages, flattened, smooth ; the third begins like the first, then 

 spreads somewhat, but ends much compressed ; p, an abnormal specimen 

 found by Mr. Cuming in a hole, from deep water, and figured in Trans. Zool. 

 Soc. vol. i. pi. 28. f. 8 ; the long spines are curved backwards over the flat 

 shell, and the cup is extremely prominent ; the dotted line represents the 

 outline of a shell at the opposite extreme, var. compresso-conicum, Proc. 

 Zool. Soc. 1856, p. 167. 



