637 



MALLEACEA. 



MALLEACEA. 



638 



_ 3f. vulgaris is the most common species, and we subjoin an illustra 

 tion as an example. It is found in the East Indian and South seas. 





ifallcus vulgaris. 



a, Valves closed, showing the byssus ; ft, inside view of valve, showing the 

 hinge and muscular impression. 



Oervillia (Fossil only). 



Inoctramut (Parkinson). (Fossil only). Though some malacologists 

 consider fnoceramut and Catillus to be identical, M. De Blainville, 

 M. Rang, and M. Deahayes consider them as distinct species, and as 

 belonging to this family. M. Deshayes gives the following description 

 of Inoceramut : 



Shell gryphoid, inequivalve, irregular, subequilateral, with a 

 lamellar shell, pointed anteriorly, and enlarged at its base ; umbones 

 opposed, pointed, and strongly recurved ; hinge short, straight, narrow, 

 and forming a right angle with the longitudinal axis, with a series of 

 crenulationa gradually smaller for the reception of a multiple ligament. 

 Muscular impression unknown. The species are of moderate size. 



Inoceramui tulcatia, natural size. From the Folkestone Blue Marl. 

 The smaller specimen ihows the hinge of one valve, the other valve being 

 a cast. 



Dr. Mantell records several species in the Chalk, two in the Chalk- 

 Marl, two in the Gault or Folkestone Marl, and one (from Martin) in 

 the Shanklin Sand (Lower Qreensand). (' Organ. Remains of Sussex,' 

 ' Geol. Trans.,' 1829.) Some of the species in the Chalk /. Bronyniarti. 

 I. Lamarckii, and /. Mytiloidei are Catilli. Professor Phillips records 

 three (one a Catillut) in the White Chalk, one in the Red Chalk, and 

 one in the Lias. (' Geology of Yorkshire.') Mr. Lonsdale notices two 

 in the Lower Chalk (Oolitic District of Bath). Dr. Fitton records six 

 named species and one undetermined from the Upper Greensand, 

 Gault, and Lower Greensand. (' Strata between the Chalk and Oxford 

 Oolite,' in ' GeoL Trans.,' 1838.) In Tenant's 'List of British Fossils ' 

 17 species are recorded as present in the Cretaceous Group. Woodward, 

 in liis 'Treatise,' says there are 40 species. 



Catillut (Brongn.). (Fossil only). M. Deshayes thus defines Catillus: 

 Shell sometimes flattened, elongated, or suborbicular, sometimes 

 convex, cordiform, subequivalve, inequilateral, with umbones more 

 or less projecting. Hinge straight, a little oblique or perpendicular 

 to the longitudinal axis, its border furnished with a row of small 



cavities which are very short and gradually increasing ; structure of 

 shell fibrous ; muscular impression unknown. 



M. Deshayes observesthatamong the genera proposed by Mr. So werby 

 in bis ' Mineral Couchology,' there is one to which he has given the 

 name of Pachymya. This genus appears to M. Deshayes to possess all 

 the external characters of Catillus, and he states that he has been led 

 to remark the approximation of that genus to Catillus by studying a 

 fine specimen in the collection of M. Duchastel. M. Deshayes proceeds 

 to observe that M. Brongniart has established a genus under the 

 name of Mytiloides for those Catilli which are very much elongated, 

 and that consequently the genus Mytiloides cannot be retained. The 

 genus Catillus then, as reformed by M. Deshayes, will consist of the 

 genera Pachymya, Mytiloides, and Catillus. Some of the Catilli are of 

 enormous size, and are mentioned as being many feet in length. 

 M. Deshayes thinks that the animals of Inoceramus and Catillus both 

 wanted a byssus. 



C. Cuvieri, may be taken as an example. It is found in the White 

 Chalk in England and France. 



Oatillm Cuvieri. a, the hinge. 



Pulrinites (Defrance). (Fossil only). Animal unknown. Shell 

 delicate, rounded, equivalve, subequilateral, with the umbones inclined 

 a little forwards ; hinge composed of eight or ten divergent teeth, 

 'orming so many pits. 



PuMnites Adamonii. Inside view of valve. 



The genus Avicula, which is placed by Lamarck among his italic- 

 cea, but is arranged by M. De Blainville, with many of the genera 

 bove described, under hia family Margaritacea, is separated by M. 

 lang into a family which immediately succeeds the Malleidce under 

 tie name of Avicule"s, containing the sub-genera Avicula (properly so 

 ailed) and Meleagrina [AviCHLA.] 



The following is M. Deshayes' description of the genus : Animal 

 val, flattened, having the lobes of the mantle separated throughout 

 leir length, thickened, and fringed on the edges ; body very small, 

 aving on each side a pair of large branchiae, nearly equal ; mouth 

 val, rather large, with foliaoeous lips, and with a pair of labial palps 

 n each side, which are large and obliquely truncated ; foot conical, 

 ermiform, rather long, with a rather large byssus composed of stout 

 laments, united in some species at its base. 



There are about 25 recent species known, and 300 fossil species. 



M. Deshayes, in his ' Tables," states the number of recent Aviculce 

 ncluding Mdeagrina) at 30, and gives 5 as the number of fossil 

 tertiary). In the last edition of Lamarck he makes the number of 



