120 CAMFOKNMA \<Anr.M\ 1)1 S( II.M l,S. 



51. Mytilimeria nuttalli Connul. 



I'l.ATK XVII. ri.i. 8. 



Mylilintfria ;/«//<i/// CoN., Joiirn. Phil. Acarl. Sci.. Vol. VII. 1S37, p. 247. Cpr., Rrit. Assn. Rcpt.. 

 I sr.;,. p. 63S. (Mini. Pal. Cal., Vol. II, p. 90. 1S69. Trvon. Syst. Conch., Vol. Ill, 

 1SS4. p. 147, PI. CVIII.ti^'. 68. Cooper, 7th Ann. Rept. Cal. St. Min., 1888, p. 252. 

 Kf.kp, West Coast Shells, p. 203. 1892. 



.Shell small, c(iuivalve. sulioval. convex, thin; beaks central, subspiral, small; surface sculp- 

 tured !))• tine, concentric, incremental lines anil nuinerous delicate radiating sulcations, the whole 

 having a pearly luster; hinge edentulous, with a slight linear cavity under the beaks; pallia! sinus 

 broad, obtuse. 



Dimensions. — Long. 11 inni.; all. 17 n)ni.; diani 10 mn). 



Tliis fi'Mi^ilo little slioll rof^onihlc'' a very small and hrnad Mi/tihiii, hut i.s ca.sily 

 (ii.slini;uisli;il)lc' hy its (lelicalo .■sculpture. Specimen.s identified hy Dr. Dall. 



Rare in the Pliocene and lower Ran Pedro series of Deadinan I.slaiid, and in 

 tlie lower San Pedro series of San Pedro. 



The species fii^iired is imperfect. It came from the lower San Pedro series at 

 Dead man Island, and is now in the collection of Delos Arnold. 



JAving. — Straits of Fiica to San Diego (Cooper). 



Pleistocene. — San Pedro (Cooper; Arnold). 



Miocene. — Tomales, Marin ("oiinty (Cooper). 



Supcrfamily POROMYACEA. 

 Family XVII. VERTICORDIID.E. 



Genus Verticordia .S'. Wood. 



Shell suborbicular, with radiatinj.; rijjs; beaks subspiral; margins denticulated; interior 

 brilliantly pearly; hinge with one prominent cardinal tooth in each valve; adductor scars two, faint; 

 pallial line simple; ligament internal, oblique; epidermis dark brown. 



Type, Verticordia cnrdiiformis Wood. 



52. Verticordia novemcostata Adama <L- Reeve. 

 I'LATK .wii, ¥u.. 10. 



Verticordia novemcostata Ad. & Rve. = V. ornata D'Orr. {JideCTR., Brit. Assn. Rept., 1S63, p. 645.) 



Shell small, suborbicular, compressed, thin; beaks subcentral, subspiral, small, sharp, 

 anterior extremity evenly rounded; posterior dorsal margin evenly arcuate, and joining arcuate 

 ventral margin in an angular extremity; surface with nine prominent, sharp, arcuate, radiating ridges; 

 the first and third interspaces wider than the others; margins sharply denticulate; hinge with one 

 prominent cardinal tooth in each valve; adductor scars two, faint; pallial line simple; ligament 

 internal, oblique; interior pearly. 



Dimensions. — Long. 4 mm.; alt. 3.5 mm.; diam. 2 mm. 



