TRANSACTIONS OF WAGNER 

 858 



TERTIARY FAUNA OF FLORIDA 



Carpenter referred it to M. tnutcata as a variety, and Grewingk figures an 

 unusually pointed specimen as M. arenaria. 



It occurs recent and in the Miocene of Unga Island, Alaska, and also in 

 the Alaskan Pleistocene. Since LI. arenaria was accidentally introduced into 

 Californian waters it has spread remarkably and is reported to have reached 

 the coast of Oregon. 



Mya producta Conrad. 

 Mya producia Conr., Fos. Medial Tert., p. i, pi. i, fig. i, 1838; Proc. Acad. Nat. Sci. 



Phila. for 1862, p. 572, 1863. 

 Mya pralonga Conr., Bull. Nat. Inst., ii., p. 185, 1842 ; name only. 



Miocene of Yorktown, York River, Virginia, Wagner ; Patuxent River, 

 St. Mary's County, Maryland, Conrad and Burns. 



This is a very distinct species, and seems to be very restricted in its dis- 

 tribution. 



Mya montereyana and stibsinuata Conrad, from the Miocene of Monterey, 

 California, are poorly described, badly figured, and have not since been identi- 

 fied (cf Pac. R. R. Reps., vi., p. 70, pi. 2, figs. 4, 5, 1S57). Mya crassa 

 Grewingk (Verh. Rus. Min. Ges. fiir 1848-9, p. 355, pi. 5, fig. \ a-d, 1850), 

 from the Miocene of Alaska, appears from the figures to be distinct from 

 M. intermedia. Mya bilirata Gabb, from the Miocene of California, is said to 

 be a Sphenia. Mya abnipia Conrad (1849, not 1856) is a Panopca from the 

 Miocene of Astoria, Oregon. Mya reflexa H. C. Lea, from the Miocene of 

 Petersburg, Virginia, is a doubtful species, the description and figure being 

 insufficient to determine its generic place. (See Trans. Am. Phil. Soc, ix., p. 

 236, pi. 34, fig. 10, 1845.) Mya simplex Holmes, from the Pleistocene of 

 South Carolina, is a synonyme of Fidcrella simplex. 



Genus PLATYODON Conrad. 

 Platyodon Conrad, Journ. Acad. Nat. Sci. Phila., vii., p. 235, 1837 ; Carpenter, Suppl. 

 Rep. Brit. As., p. 637, 1863. 



Differs from Mya by its sculpture, irregular pallial line, and the presence 

 on the distal end of the siphons of valvular horny appendages which some- 

 times are more or less testaceous. These appendages are analogous to those 

 of Tresus and some Pholadacea, and are doubtless due in all cases to the same 

 dynamic and selective influences. There is but one species known, P. cancel- 

 latiis Conrad {pp. cit., p. 236, pi. 18, fig. 2), which is found recent and in the 

 Californian Pleistocene. 



