]M A L L E U S . 



Genus MALLEUS, Lamarck. 

 Testa irregularis, snbaqnivalvis, elongata, ad basin interdum 

 ulri/iqiie lobata, umionibus divaricalis. Cardo edentu- 

 lus, Ugamento partim externo in area, declivi, partim 

 interna in fossnld unicd centrali, lacuna parvuld pro 

 bysso. Impressio mnscularis cotnposita. 

 Shell irregular, nearly eqnivalve, elongated, sometimes 

 lobed on each side, umboes divaricate. Hinge tooth- 

 less, with the ligament partly external on a sloping 

 area, partly internal within a single central pit, with 

 a small passage for the byssus. Muscular impression 

 compound. 

 The present genus was founded for the reception of two 

 oyster-like shells of very remarkable longitudinal growth, 

 of which the hinge portion or base is prolonged at a right 

 angle on each side into a narrow lobe. The term Malleus, 

 signifying a mallet or hammer, aptly designates this form. 

 Curiou.s enough, however, in none of the species since dis- 

 covered, bearing the same natural aiRuities in other re- 

 spects, is the hinge-base lobed. The M. anatinus may be 

 said to be slightly lobed on one side, but the lobe is 

 webbed, and there is therefore no outline of the hammer 

 structure. The central hinge-cavity is constant throughout 

 the genus, and all the species commence from the umboes 

 with a couceutric laminated plan of growth. In the small 

 species this laminated growth soon terminates, forming a 

 kind of nucleus, and the remaining portion of the shell is 

 au independent, transparent deposit of simple calcareous 

 matter, often characterized, however, apart from the body 

 of the shell, by a different speciality of colouring. 

 The Midhi are found in both hemispheres. 



Species 1. (Mus. Cuming.) 

 Malleus ALnus. Mall, testa longissimd, ad latera coni- 

 presse undatd, hasi utrinque angnste lobata, lobis pra- 



longis, laevigata ; sordid!} alba. 

 The -white Malleus. Shell very long, compressly 



waved at the sides, base narrowly lobed on each side, 



lobes very long, smooth ; dull white. 

 Lamakck, Anim. sans vert. vol. vii. p. 91. 



Ostrea Maliens-albus, Chemnitz. 



Varietas Malleus vormalis, Lamarck. 

 Hab. Philippine Islands ; Cuming. 



The shell figured by Mr. Sowerby in his ' Genera of 

 Shells,' and by myself in ' Conchologia Systematica,' as 

 M. normalis, Lamarck, is a distinct species, described in 

 1785 by Chemnitz, for which see M. anatinus. 



Species 3. (Mus. Cuming.) 



Malleus legumen. Mall, testa longissimu, tenui, sub- 

 laminatd, ad latera recta, prope umbones distortd, con- 

 centrice rude plicato-laminatd ; alba, nucleo laminato 

 purpurea. 



The pod Malleus. Shell very long, thin, slightly lami- 

 nated, straight at the sides, distorted near the um- 

 boes, concentrically rudely plicately lamiuatcd; white, 

 laminated nucleus purple. 



Hab. Philippine Islands ; Cuming. 



This singular species has a roughly laminated nucleus 



at the commencement of its formation, after the manner of 



some of the small Pernee. The valves are then produced 



of a thin, semitransparent, brittle substance, into a long 



pod. 



Species 3. (Mus. Cuming.) 

 Malleus anatinus. Mall, testa elongata, oblique rude 



cuntortd, ad latera subundatd, basi ad latus posticum 



alato-lobatd ; livido-albd, subpellucidd, maculis purpu- 



reo-nigris aspersd. 

 The duck Malleus. Shell elongated, obliquely rudely 



twisted, somewhat waved at the sides, base wing-lobed 



on the posterior side; livid-white, subtransparent, 



sprinkled with purple-black spots. 

 Lamarck, Anim. sans vert. vol. vii. p. 93. 



Ostrea anatina, Gmelin. 



Anas domestica, Spengler. 



Ostrea Jigurata, Chemnitz. 



Malleus normalis, Sowerby (not of Lamarck). 

 Hab. Moluccas. 



This species may always be recognized by its purple- 

 blotched colouring. The hinge-base is lobed on the pos- 

 terior side, but the lobe is webbed, so to speak, so as to 

 become winged. 



November, 183S. 



