70 MAZATLAN BIVALVES 



Genus CYTHEEEA, Lam* 



Cytlierea, ex parte, Lam. 1809, et auct. 



Meretrk, Lam. 1799 ; Desk. B. M. Cat. Ven. p. 34. 



This geuus, as restricted, is known by the subtrigonal form, 

 crenated posterior and distant anterior tooth, and the verj' 

 small paUial sinus. 



100. Cythebea petechialis. Lam. 



Lam. An. s. Vert. ed. Besh. vol. vi. p. 299.--Sozf_. Gen. f. L- 

 Hanl. Bescr. Cat. p. 96 -.—Wood Suppl. pi. lo, i. 9.— ^^'f- 

 Conch. S,jst. vol. i. pi. 69, 70, f. 1.-.? Smc. TJies. Conch, p. 619, 



pi. 129. f. 51. ... T^ 7 13 ir 



MeretrLx petichialis, Enc. Mith. pi. 268, f. 5, Q.-Desh. B. M. 



Cat. Ten. p. 36, no. 4. 



The widelv extended form to which this shell belongs was 

 distributed by Lam. imder the species Insoria, petichialis^ im- 

 pudica, castanea, zonaria var. 1. meretrix and graphica.— Uesn. 

 in his edition of Lamarck regarded the 6 last, and C. lusoria 

 probablv, as aU varieties of one species, differing only m colour, 

 and displaying insensible gradations even in this. In tlie 

 B M Cat Ten. however he pubhshes them aU as distinct ^ex- 

 cept meretrix which is merged into M.impudica) along witli 

 C. fusea. Kocli in Blul. AhhiU. Conch, p. 19, pi. 3 t. l.-^ow. 

 unites C. graphica with C. petichialis, C. fusca with C. lusoria, 

 C. castanea with C. impudica, adding C. formosa on lus ^.^ra 

 authoritv. and yet "being almost persuaded that all these, 

 along with C. meretrix, morphina, zonaria, casta and ovum 

 Hani "might be united under one name, seemg that tlie> 

 pass imperceptibly into each other, and that i^L^^yoimg state 

 it is almost impossible to distinguish them." H the varieties 

 would arrange themselves into zoological provinces, there 

 woidd be more hope of finding specific types ; but I am imable 

 to find auv difference between the Mazatlan shells and those 

 from the Cliina and Japan seas. I found scarcely a dozen 

 specmiens in the D. chiona^a box of the Liverpool collection ; 

 but several more were seen mixed with the other Mazatlan 

 shells in the shop of a dealer who had surreptitiously obtained 



• The familiar Lamarekian name ("nom plus co°^^°f ?,^;' ^'"-^^ifo^J^tf: 

 because a man ouL-ht to be aUowed to alter hi3 own work it lie can ™prOve it 

 aa he certainly dicf in this instance, by re ectmg a meretricious "'F'f/or J » l^eaU" 

 ?^uTa group of shells. There is nothing unerase >^ °»{,"" = 'V' ^"^-^ "^"^ ' 

 corrupt ideas tliat see unclean images in the purity of God s works. 



