REPORT 1856. 



PLATE VII. 



Fig. \a. Cyena ikfea?tcana, Brod. & Sby. Two young specimens laid together at the left 

 angle between the dorsal margin and the umbo : n, normal ; e, elongated. 

 In this state it forms part of C. Floridana, Desh. MS., non Conr. 



Fig. 1 b. Four specimens, similarly placed, adult : n, the largest shell, normal shape ; 

 e, elongated ; r, rounded ; a, an extreme form, described by Dr. Goidd as 

 C. altilis. The Cyrena are generally very regular shells. 



Fig. 2. Two specimens of Avicula sterna, Gould : the black line, normal ; the dotted 

 hue, with the characteristic tail almost evanescent, while the upper ears 

 are enormously developed. 



Fig. 3. Gadinia pentegoniostoma, Sby. : a, normal state, round, margin deeply 

 crenate, ribs deeply grooved internally ; these characters pass away more 

 or less in the other specimens ; b, with one corner ; c, w ith two comers ; d, 

 with three corners ; e, with four comers ; /, with five corners ; g, with six 

 corners obscurely marked. 



Fig. 4. Glyphis inaqualis,' Sby., including Fissurella pica, Sby., and F. mus, Rve. : 

 a, extreme form, type of F. incBqualis, oblong, with faint sculpture, shown 

 at a, and trilobed hole ; b, lobes of hole evanescent ; c, form F. mus ; 

 d, tj'pe of F. pica, oval, with rounded hole and strong scidpture shown at 

 d' ; e,f, g, h, i, k, I, m, n, internal views of the hole and callosity, mag- 

 nified, showing the great changes of form, and the development or absence 

 of the posterior truncation and pit. This, with an oval hole, are con- 

 sidered generic chaiacters by Messrs. H. & A. Adams : vide Gen. vol. i. 

 p. 447 (as Lucapina, but not' of Gray, except L. crenulata). 



Fig. 5. Fissurella rugosa, Sby., including F. chlorotrema, Mke., F. humilis, Mke., 

 and F. viminea, Mke. non Rve. : a, finely grown, with faint, flattened, 

 smooth ribs, and trilobed hole ; b, normal state, ribs faint, hole suboval ; 



c, specimen of irregular growth, normal outhne when young, ribs stronger ; 



d, specimen with ribs on the upper portion strongly developed ; e, speci- 

 men of coarse growth, ribs nodulous ; f, extreme form, from which the 

 species was described, ribs very strong and irregular. The coloiu- varies 

 from uniform green to nearly uniform red ; the young shells being gene- 

 rally green with a red patch, g, h, i, k, interior sketches of hole and cal- 

 lositj'. The shape of the hole is generally a very constant character in 

 Fissurellida;. 



PLATE ^ail. 



Fig. 1. Development and varieties of Crepidula nivea, C. B. Ad., including Calyptraa 

 squama, Brod., Calyptreea Lessonii, Brod., and Crepidula striolata, Mke. 

 {=zCrypta nivea, lanacus squama, and lanacus Lessonii, H. & A. Ad.) : 

 a, inside view of very young specimen, deck just forming ; b, ditto, 

 a stage older ; c, ditto, older, less magnified, anterior sinus not developed 

 {Crypta, H. & A. Ad.); d, external view, showing prominent, ribbed 

 apex ; e, another specimen, rayed {squama, Brod.) ; /, group of deck- 

 margins, the horizontal hue representing the medial point; the two 

 to the right are young, magnified ; the rounding of the outhne and de- 

 velopment of the anterior sinus, made of subgeneric importance by Messrs. 

 Adams, here appear extremely variable; g, a normal specimen, margin 

 sharp ; h, the same indented by attachment to a Strombus granulatus ; i, 

 margin in layers, flattened, abnormally thickened near the umbo ; j, out- 

 side view, form striolata, the layers beginning to appear sepai-ate outside ; 

 k, layers here and there prominent, form Lessonii, shell concentrically 

 striated, and with colour rays as in e ; /, an abnormally bilobed specimen, 

 form Lessonii ; m, a specimen abnormally costated, by attachment to a 

 ribbed shell ; n, inside view of two specimens, laid with the deck-margin to 

 correspond, to show the great length of deck in the lined specimen, and 

 its shortness in the dotted one ; o, two specimens similarly laid, one long 

 and straight, the other rounded and semispiral, like Crepipatella, H. & 



