1235 



This remarkable animal is stated by Woodward (Man., p. 306) to have long 

 united siphons and a large crescentic foot such as is found in Dosinia. It ap- 

 pears to be now an inhabitant of the Indo-Pacific and west American regions 

 only, but in Eocene and Oligocene times was well represented in tropical 

 northeastern America. Dental formula L - IOIOI -. 



R. oioioi. 



Shell thin, inflated, with prominent beaks, a ligament external and enfold- 

 ing the resilium and extending slightly in front of the beaks ; the anterior left 

 and two posterior right hinge-teeth more or less bifid; there are no lateral 

 teeth; the pallial sinus is long, angular, narrow, ascending; valve-margins 

 entire, and the valves delicately sculptured, concentrically striate or undulate, 

 sometimes with oblique decussating striae. 



dementia dariena Conrad. 



K 

 Meretrix dariena Conrad, Pacific R. R. Rep., v., p. 328, pi. vi., fig. 55, 1856; not op. cit., 



vi., p. 72, 1857. 



dementia dariena Gabb, Jour. Acad. Nat. Sci. Phila., 2d Ser., via., p. 344, pi. xliv., fig. 

 16, i6a, 1881. 



Eocene (?) of Gatun, on the line of the Panama Canal, Newberry; Oligo- 

 cene of Vamos-a-vamos, near the canal, R. T. Hill; of Sapote, Costa Rica, 

 Gabb ; of Santiago de Veraguas, Isthmus of Darien, O. Hershey. 



This appears to be a quite characteristic fossil of the middle American 

 Oligocene and has been well figured by Gabb. 



Clementia tseniosa Guppy. 

 Arcopagia tceniosa Guppy, MS. 

 Clementia tceniosa Guppy and Dall, Proc. U. S. Nat. Mus., xix., p. 327, pi. xxx., fig. 8, 1896. 



Tertiary (Oligocene?) beds of Savaneta, Trinidad; Guppy. 

 This is a more trigonal form than any of the others, but there is little doubt 

 that it is a species of Clementia. The type is in the National Museum. 



Clementia inoceriformis Wagner. 

 Venus inoceriformis Wagner, Journ. Acad. Nat. Sci. Phila., viii., p. 51, pi. i., fig. I, 1839; 



(extra copies, p. 2, pi. ii., fig. 2, 1838?) Trans. Wagner Inst. Sci., v., p. 7, 1897. 

 Clementia inoceriformis Conrad, Proc. Acad. Nat. Sci. Phila., xiv., p. 575, 1864; Meek, 



Checkl. Mio. Fos., p. 10, 1864; Dall, Trans. Wagner Inst. Sci., v., p. 8, 1897. 



Miocene of Porto Bello, St. Mary's River, Maryland, Wagner; also one 

 mile above Plum Point, Maryland, in the layer of clay below the Miocene marl, 



