2 Dr. P. P. Carppnter on nfir Forms of MuUnsca 



callosa, Bi'it. Assoc. Pi.ep. 1857 (from fragments) : non Venus cal- 

 lusa (as of Conr.), Sow., Rve., Desh. 



Hub. Sta. Barbara (Nuilall, Jewett) ; S. Pedro {Cooper) ; Cape 

 St. Lucas [Xantus). 



This section differs from the typical CaJlista as does Merce- 

 naria from Venus. Whether the other peculiarities of the spe- 

 cies (redescribed by lleeve as Cytherea nobilis) are coordinate, 

 cannot yet be stated, as it stands alone. In sculpture and colour 

 it reseaibles Dosinia ; in its ponderous growth, Pachydesma. 



110. Lazaria subquadrata. 



L. testa extus Carditx variegatas juu. simili ; pallida, castaneo tincta; 

 subquadrata, antice truncata, subregulariter ventricosa, dofsaliter 

 tumida ; costis radiantibus circ. xiv.-xvi., tumidis, nodosis, dia- 

 gonalibus majoribus ; interstitiis plus minusve insculptis : intus, 

 valva dextra dents cardinali triangulari, inter duas fossas site, baud 

 elongate ; dent. lat. a cardine separatis, ant. extante, post, obsolete, 

 calloso : v. sinistral! dent. card. ii. angustis, subsequalibus, radi- 

 antibus; lat. ant. et post, extantibus : cicatr. adduct. subrotun- 

 datis. Long. 'SJ, lat. •25, alt. '34. 



Hab. Sta. Barbara [Jewett] ; Monterey, and along the coast to 

 S. Pedro (State Coll. no. 403) [Cooper). 



The outside of this remarkable little species is typically Car- 

 ditoid; the hinge is intermediate between ia^aha and Cypri- 

 cardia. 



1 32. Modiola fornicata. 



M. testa curta, Isevi, latiore, maxime fornicata; pallida carnea, epi- 

 dermide rufo-fusca, rugis incrementi et inciustatione densissime 

 pilosa induta ; umbonibus maximis, spiralibus, antice torsis, per 

 tres quadrantes totaj latitudinis devectis ; area ligamentali curtis- 

 siraa, arcuata ; margine dorsali antice nullo, postice longo, arcuato; 

 margins ventrali recto, vix propter byssum hiante ; postico late, 

 antico angusto ; altitudins dorsaliter valds elevata, ventraliter 

 plane declivi, cuneiformi ; umbonibus trans margineni anticum per 

 sextantem totius longitudinis excurrentibus : intus, sub umbonibus 

 excavata ; cicatr. adduct. ant. ventraliter sita. Long. 1 '4, lat. • 76, 

 alt. -95. 



Hab. Sta. Barbara [Jewett); Monterey [Taylor). 



160. Pecten (?var.) cequisulcatus. 



J", testa P. ventricosa simili, sed tsnuiors, minus ventricosa ; costis 

 piuribus angustioribus xx.-xxi. ; interstitiis (prEscipue valva su- 

 periors) fere sequalibus ; auriculis magis productis, acutis; sinv 

 eerrato : testa jun. interstitiis alls insculptis, lauiinis concentricij 



280 



