or SOUTHEEN INDIA. 21 



opposite Talves. Above these teetli there is a small cartilage lodged. I have seen 

 ouly large specimens of Conrad's type Parapholas Califor)iicus, and these do not 

 show any teeth, but a cartilage below the beaks ; the shells of the pholadinje 

 change, however, so much with age, that I could not feel certain in proposing a new 

 generic name for our shells unless I had the opportunity of examining yoimg and 

 fresh specimens of the above-mentioned tyjie species. 



10. Pholadidea, Turton, 1819, (H. and A. Adams, Gen. ii, p. 328). Shell 

 very similar to Martesia, the two dorsal accessory valves are smaller than in 

 ParapJiolas ; the posterior end is enlarged into a cup-shaped appendage protecting 

 the siphons. 



Tryon in his last review of the P eoladid^ in American Journ. of Conch, 

 (vol. iii, 1867, part 3), quotes the following sub-genera of this genus; Satasia, 

 Gray, Talonella, Gray, Netastomella, Carpenter. The differences of these from the 

 type genus appear to be of Little importance. I shall only refer to the last one ; of 

 the fli'st Ph. melanura, Sow., of the second Ph. tridens, Sow., are considered as types. 



lOffl. Netastomella., Carpenter, 1865, (Proc. Zool. Soc, p. 202,) is based upon 

 Pholas Danoinii, Sow., the valves of which are posteriorly prolonged into a 

 flattened calcareous cup. It is said to differ from Jouannetia in having both valves 

 equal, and from Pholadidea by the calcareous nature of the cup at the posterior 

 end of the shell. 



11. Penitella,Y?i\.Qnc., 18?? (Conrad, 1849,- see Tryon's Memoir on the 

 PaoLADiBM in Proc. Phil. Acad, for 1862). Shell very similar to that of the 

 previous genus, slightly expanded posteriorly ; one umbonal and two pre-vimbonal 

 accessory valves, placed side by side, are present. 



12. Talona, Gray, 1840, (H. and A. Adams, Gen. ii, p. 329). Shell in form 

 resembling Pholadidea ; anterior liiatus open, very small ; pre-vimbonal margins of 

 the valves reflexed ; two small umbonal plates side by side ; posterior end enlarged, 

 cup-shaped, and protected by a pair of siphonal valves. 



13. Navea, Gray, 1851, (ibid., p. 328). Shell small, sub-ovate; one small 

 post-umbonal accessory plate ; anterior hiatus ^videly open. 



14. Barnea, Leach, 1826, (ibid., p. 326). Shell elongately ovate; one 

 narrow and long umbonal accessory plate ; umbonal processes thin, reflexed. There 

 are two slightly different types of shells referred to this genus by Tryon. The one 

 kind, like B. Candida, L., has the margins of the valves rounded, and the anterior 

 hiatus is long and narrow ; these shells are considered to be typical Barnece. 



14a. The other form, represented by B. parva, L., has the antero-ventral 

 margin insinuated, and the anterior hiatus is short and wide. Eor this last the 

 sub-generic name Anchomasa, Leach, has been adopted. 



146. Ilonothyra, Tryon, 1862, (Proc. Phil. Acad.) may be considered as a 

 third form of the same general type ; it only diffei's from typical Barnea by having 

 the umbonal plate larger, cuneiform, and the umbonal processes cellular. Pholas 



