CARDIUM. Auct. _Fam._ Cardiacea, Lam. Conchacea, Bl.--_Descr._ Equivalve, sub-equilateral, sometimes gaping posteriorly, ornamented on the outside by ribs radiating from the umbones; cardinal teeth, two in each valve, locked into each other crosswise, lateral teeth, two in each valve, remote; muscular impressions, two in each valve; palleal impression entire. Ligament external, inflated.--_Obs._ Although this genus includes many remarkable forms, the characters are so easily defined that there is no difficulty in distinguishing it from any other genus. C. angulatum, fig. 123. C. Groenlandicum, fig. 123*. APHRODITA, Lea. C. Hemicardium, fig. 123**. fig. 122. C. Dionæum. It is somewhat surprising that this genus, which contains some of the most beautiful forms of bivalve Testacea, should have been left till quite lately without any attempt to revise the species and settle the synonyms. The author of this Manual has endeavoured to remedy this defect by publishing a catalogue of all the species hitherto known, which amount to 97, including many new species described by him in the "Proceedings of the Zoological Society," in 1840. Parts 46 to 51, 149 and 150, and 177 to 184 of his Conchological Illustrations contain figures of 60 species. Cardia are frequent in all climates. CARINARIA. Auct. _Class_, Cephalopoda. _Division_, Monothalamia, Lam. _Fam._ Nectopoda, Bl.--_Descr._ Symmetrical or nearly so, conical, thin, glassy, fragile, patelliform; with a fimbriated dorsal keel; apex convolute, bent forwards; aperture oval, pointed at the dorsal extremity. _Hab._ Amboyna, Indian Ocean, and Mediterranean Sea.--_Obs._ A most singular and beautiful shell, remarkable for its transparency, its fragile structure, and the dorsal keel, whence it derives its name. It was once so rare that a single specimen was known to realize one hundred guineas. Fig. 488. C. Mediterranea. CARINATED. (From _Carina_, a keel.) Applied to any shell having a raised, thin ledge, passing round a whorl or any other part of a shell, as in Carinaria, fig. 488. CARINEA. Sw. A genus formed for the reception of OVULUM gibbosum, Auct. and similar species, fig. 443. CARINELLA. Adanson. LUTRARIA papyracea, Lam. LIGULA, Leach. _Fam._ Mactracea, Lam. Fig. 77. CARINIDEA. Sw. A sub-genus of the genus Canthorbis, Sw. (Turbo.) thus described, "Imperforate; spire pyramidal, acute; basal whorl concave beneath, and carinated round its circumference; aperture oval, entire, slightly angulated at the base of the pillar, which turns inwards. C. concavus, Martini, 168, fig. 1620, brevispinosus? Sow. Gen. (Turbo,) fig. 1."