C Y ^J^ II E R E A . 



Plate I. 



Cieiuis CYTHEREA, Lamarck. 



TesLa siibtrlgono-ovnla, plus minus iia-gkla, crassi/iscii/ii, 

 lcevi(jnta, rarissime scidpla, marcjinibus integris. CarJo 

 ill utrdque vnlvA tridcnlatns, denle antico subtrinoio, 

 later aliler compresso. Tmpressio pallii poslice vix 

 situiiilft. 



Sliell soiia-wliat triangularly ovate, more or less turgid, 

 rather thick, smooth, very rarely seiilptured, margins 

 entire. Hinge in each valve three-toothed, anterior 

 tooth rather distant, laterally compressed. Impres- 

 sion of the mantle scarcely sinuated posteriorly. 



Unwilling to give up the well-known generic name of 

 Ci/tlwrca, it is here used for the characteristic group of 

 smooth Veiieridcc, of which the Lamarckiau C. petucldulis, 

 impiidica, antl meri-tri.v are e.'vamples, constituting the 

 genus Merelrix of Dr. Gray, of JI. Deshayes. With these 

 are included the species, typitied by the Linnwan I'ciiits 

 tripla, and separated by those authors mider the head of 

 Trif/oita. They are chiefly natives of China and the Philip- 

 |iiue Islands. All of which we have any record of their 

 habitation in tlie Xew World arc six from Central America, 

 two from W'est Indies, and two from California. None are 

 rejrorted from Australia or New Zealand. C. tripla is a 

 native of Senegal. The only European Ci/lln'rea is C. iii- 

 lidala of the Mediterranean. 



Species 1. (Mus. Cuming.) 



Cl'THERE.i. GR.\Pinc.\. Cijih. tesld siihlrigono-cordatd, 

 postice snbprudiictd, Jlavesceiite-grised, notis fuscis 

 liinrogly phicis profuse oblique radiatii, coiicentrici 

 rugosd. 



The gk.vpuic Cythekea. Shell somewhat triangularly 

 heart-shapi'd, posteriorly somewhat produced, yel- 

 lowish-grey, profusely obUquely rayed with brown 

 hieroglyphic marks, concentrically rugose. 



Lamarck, Anini. sans vert. vol. vi, p. 300. 

 Me/'efrix graphica, Deshayes. 



Hub. Sumatra. 



Distinguished among other characters by the immerous 

 rays of hieroglyphic marks. 



idienle indutd, latere postico conspicne urcuato-pro- 

 duclo. 



The little hatchet Cytherea. Shell sharply trian- 

 gular, compressed, violet cream-colour, covered with 

 a shining fulvous-olive horny epidermis, posterior 

 side conspicuously arcuately produced. 



SowERBY, Thes. Conch, vol. i. p. 611). pi. 127. f. 19. 



Hab. Red Sea. 



This and the preceding species represent the extreme 

 forms of the genus as indicated by the subgeneric titles 

 Trii/oiia and Meretrix. It will be seen that in C. gra- 

 phica the ])osterior margin is convex, while in C. dolabella 

 it is absolutely concave. 



Species 3. (Mus. Cuming.) 



Cytherea Crassatelloides. Cytli. testa oblique oratd, 

 sububloiigd, modici irigoiid, crassd, ponderosd, veutri- 

 cosd, epidermide corned crassd indutd, epiderniide 

 lacled, purpureo-violaceo radiald. 



The Crassatella-like Cytherea. Shell oblicpielv 

 ovate, rather oblong, moderately triangular, thick, 

 heavy, ventricose, covered with a thick homy epi- 

 dermis, epidermis crcani-colour, rayed with puriile- 

 violet. 



Trigona Crassatelloides, Conrad, Ami. Xat. Sci. Phila- 

 delphia, vol. vii. p. 253. pi. 19. f. 17. 

 Cytherea Crassatelloides, Hanley. 

 Cytherea (Trigonellu) Crassatelloides, Hinds. 



Hab. Bay of California. 



The colouring of this species resides in the horny epi- 

 dermis, with which the shell is entirely enveloped. 



Species 2. (Mus. Cuming.) 



CilUEiiEA dolabella. Cyth. tesld acute trigond, coui- 

 pressd, violuceo-lacied, epidermide corned fulco-olivaced 



Species 4-. (Fig. a, b, ^Mus. Cuming.) 



Cytherea damaoides. Cyth. tesld compresse cunei- 

 forini, postice arcuato-acmnbiatd, solidiusculd, fiaves- 

 cente-spadiced, interdum carneo-fusco radiald, interdum 

 griseo profuse uitdato-puuclald. 



TuE DEER-LIKE Cytherea. Shell comprcssly wedge- 

 shaped, posteriorly arcuately acuminated, rather solid, 

 yellowish fawn-colour, sometimes rayed with flesh- 

 brown, sometimes profusely wave-dotted with grey. 



Fenus damaoides. Gray, Wood Ind. Test. Sujip. pi. 2. f. 17. 

 Cytherea damaoides, Hanley. 



Trigona damaoides, Grav. 



Hab. ? 



A solid compressed Z'owrt.f-shaped shell, in which the 

 colouring is extremely variable. 



February, 1S6+. 



