208 PROCEEDINGS OF THE CALIFORNIA 



This very distinct genus has the aspect of Theora, and appears allied to Neaera 

 It is probable that the cartilage was strengthened by an ossicle. The great pecu- 

 liarity is the twisting-in of the dorsal margin, which asceuds the umbo in a very 

 loose spiral. 



Genus Macoma, Leach. 

 Macoma indentata, Cpr. n. s. State Collection, No. 365. 



M. t. " M. sectse " simili ; sed postice valde rostra ta, sinu inter plicam et regio- 

 nem ventralem valde expansam iudentato. 



Long. 2-20, lat. 1-40, alt. 0"56. 



Hah. San Pedro, (young, living, Palmer ;) large dead valves, Cooper. 



Diners from AT. umhonella, Lam., in its secta-\lko post-ligamental wing. This 

 being rubbed ofl'in the large dead valves, the shell has the aspect of a very distinct 

 species. 



Genus (EDALINA, Cpr. 



(Edalia, Cpr., Brit. Ass. Rep., 1834. (pre-occup.) 



Subgenus Cooperella, Cpr. 



(Edalina ; cartilagine fossa semi-interna, ligameuto externo contigua, sita, ; den- 

 tibus cardinalibus lainiuatis, haud bitidis, sen uno bifido. 



Dedicated to the memory of Judge Cooper, of Hoboken, N. J., author of the 

 Report on the Mollusca of the Pacitic Railway Expeditions. 



Cooperella scintillaiformis, Cpr. n. sp. State Collection, No. 533 a. 



C. t. tenuissima, subdiaphana, latiore; forma " Scintila; Cummingii " simulante; 

 e\rus argenteo-iridescente, striulis incrementi exillimis interdum luulata ; parte 

 postica paullum majore rotundata ; intus, valva dextra dent ii. laminatis, arcuatim 

 divergentibus, extantibus, quorum anticus major, ventraliter sulcatus ; v. siuistr 

 iii., quorum ant. et post, laminati, arcuati, centralis triangularis, bifidus; fossa 

 cartilaginali parva, semi-interna, sub umbones angustiores, satis promineutes, 

 sita; lamina ligamentali nulla, nymphis longioribus ; sinu pallii oblongo, lato ; 

 linea pallii antica minus declivi. 



Long. U-60, lat. 0-48, alt. 0-32. 



Hab. San Diego ; San Pedro, 2 dredged in 8-20 fms. Cooper. 



Genus Semele, Schum. 



Semele incungrua, Cpr. n. s. State Collection, No. 1061. 



S. t. forma et indole " S. pulchrae " simili, sed sculptura diversa ; transversa, 

 tenuii, subplanata, umbouibus prominentibus; pallide carnea, radiis inteusioribus 

 ornata ; tota superficie minute et creberrime radiatim striulata; marginibus dorsa- 

 libus postico rectiore, antico parum incurvato; reliquis regulariter excurvatis, 

 parte antica diagonahter valde producta ; v. sinistr. liris crebris subacutis concen- 

 tricis, antice saepe irregulariter interruptis, postice circiter quaternis solum con- 

 spicuis, extantibus ; v. dextr. liris pancioribus, acutis, antice vix interruptis, postice 

 alternantibus, extantibus: intus; dent, card, parvis, iossa cartilaginali angusta 

 elongata; dent, lat., v. dextra, elongatis, regione cardinali purpureo tinctis ; cicatr. 



