A N M I A 



Plate I. 



Genus ANOMIA, L'nmaus. 



Testa plerumque orbicularis, inasquivalvis, irregularis, affixa, 

 interdum solidiuscula, scspissime ieauissinux, hyalina. 

 Valva inferior plana, prope cardinem orbiculatim 

 perforata et emarginata, perforatione curieoh adluB- 

 sionis suhcalcareo libere ■■ impletd. Valva superior 

 convexa, squamaio-laminala, striata ant costata, im- 

 pressionibus muscularibus friius, subcentralibus. Cardo 

 edenttdas, ligamento brevi ad callosiiatem ajfixo. 



Shell generally orbicular, iuequivalve, irregular, affixed, 

 sometimes rather solid, mostly very thin, hyaline. 

 Lower valve flat, orbicularly perforated and notched 

 near the hinge, perforation freely filled with a sub- 

 calcareous plug of adhesion. Upper valve convex, 

 squamately laminated, striated or ribbed, with three 

 subcentral muscular impressions. Hinge toothless, 

 with the ligament short, attached to a callosity. 



AnomifB are of all shells the most difficult to determine 

 the species. Liviug attached to foreign bodies, and being 

 mostly of fragile texture, the shell becomes more or 

 less shaped to the irregularities of its surface of attach- 

 ment. If growing upon a ribbed surface, the shell as- 

 sumes a ribbed structure; but the ribs formed under 

 these circumstances are not marked by the definition and 

 character which belong to a species that has a typical 

 ribbing or striation oi' its own. There is periiaps greater 

 difficulty in discriminating between tiie difl:"erent states of 

 a species incident to age and haliitat. The well-known 

 A. t'phlppiiiin of the European seas has been described 

 twenty times over. Even of the nine recent Anom'ue de- 

 scribed by Lamarck, eight are supposed to be referable to 

 this one species. 



Several important species of Anomia had been long 

 known in Mr. Cuming's cabinet, when Dr. Gray, in 1849, 

 undertook to describe them. To these a few are now 

 added, including one of large size and striking character, 

 A. nobilis, from the Sandwich Islands, and the list is ex- 

 tended to thirty-three. 



There is little to generalize u])ou in connection with 

 tlieir places of habitation. Australia contributes the finest 

 species in A. elyros, and the rest so far as the habitats 

 are known, would appear to be almost limited to the 

 shores which have been dredged by ilr. Cuming, some in 

 the New World and some in the Old. 



Other sources of information as to the localities inha- 

 bited by this genus are much needed. 



Species 1. (Mus. Cuming.) 

 This shell represents Anomia pohjmorpha of Philippi, 

 who has given definitions of seven distinct varieties. It 

 is of a thin, crystalline texture, with a well defined umbo, 

 and is found abundantly both in the interior and on the 

 exterior of shells and other marine bodies, varying in ap- 

 pearance and structure according to the irregularities of 

 its place of attachment. It has been considered by \)x. 

 Gray and by Messrs. Forbes and Hanley to be only so 

 many states of A. ephippium, and I incline to concur in 

 that opinion. 



Species 3. (Fig. a, b, Mus. Cuming.) 



Anomi.\ plenilunium. Anom. testa orbiculari, subopaco- 

 albu, Jlavicanie, versus niargimm pellucido-laminutd, 

 valva inferiore lineis Jiexttoso-radiatd. 



The full-moon Anomia. Shell orbicular, somewhat 

 opaque-white; yellowish, transparently laminated to- 

 wards the margin ; lower valve flexuously rayed witii 

 lines. 



Hab. Borneo. 



The under valve of this species is tumidly raised about 



the orifice, with flexuous lines diverghig around. 



Species 3. (Mus. Cuming.) 

 Anomia. elyros. Anom. testa subqiiadratd, ampld, crajs- 

 siusculd, radiatim dense rugoso-striatd, striis irregula- 

 ribus ; opaco-albd, valva superiore ferrugitieo tincid, 

 inferiore viresceide. 

 The Port Essington Anomia. Shell somewhat square, 

 large, rather thick, radiately densely roughly striatetl, 

 stria; ii-regular, opaque-white, upper valve tinged 

 with rust, lower valve greenish. 

 Gray, Pro, Zool. Soc. 1849, p. 118. pi. 4. f. L 

 Uab. Port Essington, Australia ; Eari of Derby. 



This fine species, of which another example in a younger 

 state is represented at I'late II. Fig. 9, is remarkable for 

 the manner in which the callous deposit of the interior is 



August, 1839. 



