CAPRELLA. ----? PLEKOCHEILUS, Guild. AURICULA Caprella, Lam. CAPRINA. D'Orb. DICERAS. Auct.? CAPRINUS. Montf. (Conch. Syst. t. 2. p. 143.) The figure appears to be intended to represent Helix Nux-denticulata. CAPSA. Brug. _Fam._ Nymphacea, Lam.--_Descr._ Equivalve transverse, subequilateral, subtrigonal; cardinal teeth, two in one valve, one notched in the other; lateral teeth remote, obsolete; an external ligament; two muscular impressions in each valve; a large sinus in the muscular impression of the mantle.--_Obs._ This genus is so nearly related to Donax, that it is difficult to distinguish it at first sight. The Capsæ, however, have not the short, plain, straight, posterior side, the distinct lateral teeth, nor the crenulated margins which characterize nearly all the Donaces. They are found in the British Channel, Brazil, and coast of Pacific Ocean. They are known from Erycina by not having the pit in the hinge for the ligament. Fig. 109. C. Braziliensis. CAPULUS. Montf. _Fam._ Calyptracea, Lam.--_Descr._ Obliquely conical, posteriorly recurved; apex pointed, sub-spiral; aperture large, rounded, oval; with two muscular impressions, lateral, meeting behind; epidermis horny, rather velvetty. Britain, Mediterranean, West Indies, California, Australia. CARDIACEA. (Cardiacées, Lam.) A family of the order Conchifera Dimyaria, Lam. Most of the genera of shells contained in this family are included in the very extensive family of Conchacea, in the system of De Blainville. They are described as having irregularly formed cardinal teeth, generally accompanied by one or two elongated lateral teeth. Most of the species are ventricose, and have regular radiating ribs. This family contains the genera Cardium, Cardita, Cypricardia, Hiatella, Isocardia, and others enumerated in the explanation of figures 122 to 130. Their characters may be thus explained. 1. CARDIUM. Two cardinal and two lateral teeth in each valve, including _Hemicardium_, _Papyridea_ and _Aphrodita_, in the last of which the teeth are nearly obsolete. Fig. 122, 123, 123*, 123**. 2. VENERICARDIA. Two oblique cardinal teeth, one elongated; including _Cardita_, which has the umbones nearly terminal. _Pachymya_ may probably be included, but the hinge is not known. Fig. 121, 124, and 130. 3. HIPPOPODIUM. One elongated cardinal tooth. Fig. 129. 4. MEGALODON. Hinge broad, septiform, with a large tooth in the centre of one valve. Fig. 127. 5. ISOCARDIA. Teeth laminar; umbones spiral. Fig. 126. 6. CARDILIA. The same, with a septiform posterior laminar tooth. 7. HIPPAGUS. Shaped like Isocardia, without teeth. Fig. 128.