132 Journal of the Mitchell Society [February 



rected upward and outward so that they look like a dead stump or part of 

 the fan. 

 Although Stimpson and Coues report Pteria cohjmbus (Dillwyn), I was unable 

 to find a trace of it. The material which I have called P. eximia agrees 

 perfectly with Ree\e's A. eximia and the specimens were quite common 

 on the fans. I have been unable to find any mention of this form. If 

 Reeve's name should be preoccupied or subsequently taken, I would call 

 the species P. eximioides. Some of my material has been deposited in the 

 American Museum under Cat. No. 4998. 

 Oslrea virginica Gmelin. S C O A J 



Md. Geo. Sur., Plio.-Pleistocene, pis. 61-63. 



Abundant inside, mostly on mud flats, forming extensive banks locally called 

 "rocks." 

 Oslrea equestris Say. S C 

 See Coues. 



"Abundant; adhering to rocks with Modiola and Mytilus." 

 Pecten {Plagioctenium) gibbus irradians Lamarck. S C J 

 Rogers, Shell Book, p. 411, fig. I. 



Abundant, outside, inside on sand in the deeper water. 



Normal number of ribs is 18-20, most common number is 19; rarely brilliant 

 as P. gibbus; prefers open, clear water, and usually a greater depth than 

 P. gibbus. 

 Pecten (Plagioctenium) gibbus gibbus Linne. S C O A J 



Common, inside on quiet mud flats, west of Fiver's Island. 

 Normal number of ribs is 19-22, most common number is 20, usually brightly 

 colored, shows preference to quiet water. 

 Pecten yiodosus Linne. S C J 



Rogers, Shell Book, p. 418, fig. 1. 



Coues reports a beach worn valve; half a fresh valve was picked up on Shackle- 

 ford Bank in August, 1916. 

 Plicalula gibbosa Lamarck. S C J 

 Figures 85. 

 Occasional inside. 

 Lima inflata Lamarck. S C J 



Rare, inside, largest have a vertical height of 14 mm., the riblets are obsolete 

 through the center of the disc. Live specimens found by Dr. Hyman 

 differ in being relatively stouter, more inflated, broader, and in being cov- 

 ered by rounded, unequal, radial wrinkles. Vertical height, 13 mm. 

 Anomia simplex Orbigny. S C O A J 



Rogers, Shell Book, p. 419, figs. 4 and 6. 

 Abundant inside. 

 Mytilus (Hormomya) exustus Linne. A J 

 Figures 1, 2 and 3. 

 Common, on breakwaters. 

 Stimpson and Coues report Mytilus cubitus Say {Modiolus citrinus Bolten) 



probably for this species. 

 They also report Mytilus edulis. 

 Mytilus recuruus Rafinesque. C J 



