386 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvi. 



TIVELA DELESSERTI Deshayes, 1854. 



Scammoivf-i Lugoon (young-!;); Cape 8t. Lucas, the Gulf region, and 

 south to Acapulco. 



This is the Cytherea nitidula Sowerby, 1851, not of Lamarck, 1.S18; 

 the 3'oung f r}^ were named Tivela inarglnatd I)}' Carpenter, ])ut 1 do 

 not find that this name has ever been defined in print. It is an elegant 

 polished shell, delicately painted with light purplish brown on a cream- 

 colored ground. 



TIVELA (PACHYDESMA) STULTORUM Mawe. 



Santa Cruz, California, and south to Ballenas Lagoon, Lower Cali- 

 fornia, and perhaps to Mazatlan. 



This is the Donax stultoruni of Mawe in 1823, but not the Tivela 

 stulioruni of Menke in 184T; the Trigonella crassateUoide.^ Conrad, 

 1837; 6'y^7i6T6?<* 6Y>//c//.w//;^t« Philippi, 1851; C. sequilatera Romer, 1857, 

 not of Deshayes, 1839; C.la/j/arch'i, O. sti/Itorum, and O. crassatelloides 

 of Reeve in 1861. This is the largest and finest species of the genus, 

 and is well known to most conchologists under the name of Puchydesina 

 ('f(i.s8ateUoides. A related fossil, P. inezana, is said by Conrad to exist 

 in the California Miocene. 



MACROCALLISTA (CHIONELLA) SQUALIDA Sowerby, 1835. 



Cerros Island, Pacific coast of Low^er California, to the Culf and 

 southward to Peru, in 7 to 27 fathoms. 



Chione hlradlata Gray, 1838, and Cytherea ddonoia Menke, 1847, 

 are synonymous. The Philippine C. elegana Koch, in Philippi, 1814, 

 has been united with them, but is probably distinct. The species is 

 nmch like Macrocallista chione of Europe, but less attractive. It is 

 the analogue for the Pacific coast of M. maculata Linnaeus, of the 

 Antilles. 



MACROCALLISTA (CHIONELLA) AURANTIACA Sowerby, 1831. 



(julf of California, Cape St. Lucas, and southward to Guayatiuil, in 

 10 to 18 fathoms. 



More compressed, redder, and with a dark and dull instead of trans- 

 lucent vernicose periostracum, compared with M. .^(^tiallda. It was 

 first figured and named in Sowerby's Genera of Shells, Part XXXIII, 

 but Hanley's name of aii7X(ntia given thirteen years later has been 

 more generally used. 



MACROCALLISTA (CHIONELLA) PANNOSA Sowerby, 1835. 



Cape St. Lucas, the Gulf of California, and southward to Valparaiso, 

 Chile. 



This prett}' little species is extremely variable in its color pattern. 

 Cytherea lutea Koch, in Philippi, 1845, is synonymous. 



