til 





COXCIIIFKKA. 



lit 



D. BUtnrilU thu. divid*. the 



J. 



*rly non-xitont in 

 ow. Example, 



U of who- teeth r very Urge, UnM*. nd not 



rSh* d^olid .peoM. without an epidenni. ; the lateral 

 toMh toety *t~ted; miiU. pieroed with two opening.; but 

 I tut** Example, H. Iriftmttm. 



^jt^l n*ci*M trivvivd looirituuiiiauly \ c&rdinu 

 _ _~. or next to noniTuteral teeth rery thick, approximated, 

 rai~d. u external Ufemeot beside* the internal one. 



Mr. O. a Sowerbj" says, " The foMtl .pecie. are not numeroua ; 

 they are only found in the tertiary bed*, unle indeed some very 

 angular f.il. found in the Mcondary .irate, particularly oolite, be 

 truly refcrrible to thU g>nu ; of thin however we cannot be certain, 

 bmui w, know not their binge* ;" they will be found represented in 

 8owrby'. ' Mineral Conchology.' De Blainville quote. M. Defrance 

 for iffatoni foil specie*, one identical, one analogue in the Plaisan- 

 Ua. and another analogue " dan. la Caroline du Nord." Deahayfs 

 in hi* Table, give, fourteen foeail (tertiary) and four a. both living 

 and fowl (tertiary) : in bin edition of Lamarck but three specie, are 

 M fuMil only. Among the fomil nhclln from the border* of the 



Sea, collerUd by Mr. J. Burton and communicated by Mr. 

 to Mr. Lyell, we find M. Stultontm with a (t). Mr. Lea 

 ie*, M. dmlala, M. Grayi, and it. fygoxta, from the 



[M*CTIDJL] 



. Jhell equivalve, transverse, inequilateral, not attached 

 nor gaping. In one valve two rtrons, cuneiform, rugose, sometime. 

 p*rp*ndicuUrry-grooved cardinal teeth ; in the other only one ; liga- 

 ment internal, attached to a concave .pace placed on the anterior 

 aid* of the binge ; the pit divided by a carina into two portions, and 

 that part of UM ligament attached to the outer portion visible 

 externally when UM valve, are closed : two strong oblong depression, 

 may then be observed, on* on the anterior side of the umbo, rather 

 lnnpt.il. and not so dutinct a. the other on the posterior side 

 MiuruUr impression, two, distant, lateral, rather oblong; latera 

 teeth none, or nearly obsolete. Shell very thick, particularly in old 

 the reosot ones with a brownish somewhat horny epi 



all more or lea. tnuwrenely grooved near the umbones. 

 The apecM. are found in the MM of Australia. 

 M. Dohayea, in hi. Tablea, give, the number of living specie, a 

 The ahrll. may be dutinguisbed from Haodtnua by mean, o 



al war* i 

 Mr. ( 



C.< 





hich i. alway* .imple in the CnunttU*, an 



a Sowerby, in hi 'OeMta. 1 mention* C. tumida an 

 > from UM Caleaire Oroemer of the environs of Paris, an 

 at Hordwell, and as appearing to 



' 



characterise of the London Clay. M. Desh.ye. remark, upon that 

 .hell that Lamarck regarded the fossil, at Beauvau and those living 



t Australia as analogues ; but that he has satisfied himself that those 



oetiU and C. mlcala are different species. C. tumida, he observes, 



pproaehe* C. Ki*fficola nearer than any other. 



De Blainville .tetes that there are even at least fossil in Ki ice, 

 and that M Defrance mentions twenty from the lower chalk WIN 

 some doubt In his Tables M. Deshaye. give, twenty-four fossil 

 specie* (tertiary) : in hi. edition of Lamarck he record* fourteen 



lily. It appear* in the catalogues in the Supracretaceous and 



O^gem^bdonging to De Blainville'. Cmxkacta .will be found 

 nder LITHOPHAOID.B, and the genera separated from Venut, or allied 

 that family, under VBXERIDJL 



CONCH I'f-KKA, Lamarck's name for that Urge class of Molluscous 

 Animal, which .re protected by shell, consisting of two principal 



i commonly known under the denomination of Bivalves, 

 comprises the whole of the Acephalous Mollusks of Cuvier, including 

 the Bratkiopoda. [BRACHIOPODA.] 



Lamarck divided the class into two great orders, the IHmyan 

 Dimyaires), or Conchifera, furnished with two adductor muscles, and 

 he Monvmyaria (Monomyaires), or Conchifers furnished with one 

 adductor muscle only. M. Deshaye. would separate the class into 

 three sub-classes:!, the Polymyaria, or Brachw,xla ; 2, the 

 /Urn i/aria ; 3, the Monomyaria. He founds this order of arrange- 

 ment on the principle that the organisation of the Brackiopoda i* 

 more simple than that of the other Conchifers, while that of the 

 'Xmyaria is somewhat leas complex than that of the Jfononn 

 The two last divisions are now more generally called La 

 rantkiaia, from the fact that in nearly every case the branchiic. or 

 gills, occur in the form of four riband-shaped lamellae, two of WMBB 

 Ire attached to each lobe of the mantle. 



The following account of the structure of the Conchiftra refers 

 more especially to the Lamdlibranchiata : 



Digestive System. Mouth without any hard parts, situated ante- 

 iorly : in the Dimyarians concealed between the foot and the anterio- 

 retractor muscle : in the Monomyarians under a sort of hood made by 

 the mantle. Labial palps or lips flattened, sometimes truncated, 

 sometimes laminated internally, more or less elongated, extending on 

 either side. No salivary gland. QJsophagus varying in length and 

 capacity, often wanting altogether both in Dimyarians and Mono- 

 myarians. Stomach sometimes, not often, lengthened and narrow, 

 sometimes subcircular, generally pear-shaped ; interior surface with 

 irregular depressions, or biliary crypts. Intestine arising posteriorly, 

 convoluted within the liver and ovary, and so brought toward, the 

 back and mesial line of the animal, and continued posteriorly to the 

 vent, nearly of the same diameter all through. Rectum, which 

 commences with the dorsal part of the intestine, shorter in the 

 Monomyarians than in the Dimyarians : in the former it i. < 

 luted behind the single central adductor, and terminates in a floating 

 vent between the edges of the mantle ; in the latter the vent is 

 situated above the (uperior adductor. Liver very large, supported 

 by muscular fibres, which traverse it, pouring the bile into the 

 stomach by the biliary crypts. 



Circulatory and Respiratory System. Circulation, a simple circuit 

 of two vascular systems, namely, a ventricle and an arterial system 

 a venous system and two auricles, the ventricle firmly and closely 

 embracing the rectum, so that it appear, to pass through it The 

 arterial system not complicated, the venous system upon a consider- 

 able scale of development Circulating fluid nearly colourless, or 

 white, scarcely tinged with bluish, slightly viscid, and with very 

 little crassainentum. [BLOOD.] "Circulation then is an extremely 

 simple function in the Conchiferous Molluaks ; an aortic ventricle 

 gives the blood impulse enough to carry it through the two nystpms 

 of vessels, to expel it from the heart, and to carry it back again to 

 the auricle. In other branchiferous animals the auricle is sometimes 

 adapted to give the blood a new impulse when it is about to pas. 

 through the branchiae; here, on the contrary, the auricles do not 

 receive the blood until it has been exposed to the revivifying inti 

 of the organ, of respiration." (Deahayes.) The respiratory Cm 

 is carried on by mean, of hranchiic variously disposed. They are all 

 however disposed in a lamelliform manner. 



The reproductive system consists simply of an ovary envol^x-d in 

 the visceral mass. Taking the common oyster for example, it rests, 

 a whitish mass of considerable size, upon the adductor, and may be 

 seen through the mantle. It occupies the whole upper part of the 

 mollusk, and creeps down along the sides and lower parts, lieing 

 filled at the time of reproduction with a milky fluid, containing 

 multitudes of small globules of a whitish colour. These are the eggs; 

 and in many of the family they are not at the time of their exclusion 

 abandoned at once, but are deposited between the two membrane* of 

 the branchial lamina, where they undergo a kind of incubation. In 

 >me the ohell is developed in the ovum before it quits this receptacle. 

 Tin- fostering of the eggs seems to be analogous to the gestation of 

 the eggs in the Cnutacm and the pipe-fishes. Sir A ntliony Carlisle 

 C llmiterian Oration,' 1826) sny, "Oysters are vivip.inmw. .,,,.1 thi-ir 

 young arc found within the trachea! passages :>nd l>et.ween the folds 

 of the coverlet (mantle) during the month* of June and July 



