TRANSACTIONS OF WAGNER 

 1456 



TERTIARY FAUNA OF FLORIDA 



Ameroda Rafinesque, op. cit., p. 319; err. typ. pro Amesoda. 



Cycladites Kruger, Urwelt, ii., p. 469, Tellina cornea Linne. 



Pisum Bourguignat, Rev. et Mag. de Zool., 2me Ser., vi., p. 85, 1854, Cyclas rivicola 



Lam.; not Pisum Megerle, 1811, founded on a fossil brachiopod. 



^.Sphceriastrum Bourguignat, op. cit., pp. 668, 669, 674; Mem. Soc. des Sci. de Bor- 

 deaux, i., pp. 162, 164, 1854; Westerlund, Fauna Palsearct. reg., vii., p. 6, 1890, S. 



rivicola Leach. 

 Corneola Clessin, in Westerlund, Fauna Palsearct. reg., vii., pp. 6, 8, 1890; not Corneola 



Held, 1837- 

 ~2>Cyrenastrum Bourguignat, Rev. et Mag. de Zool., 2me Ser., vi., pp. 668, 674, 1854; 



Mem. Soc. des Sci. de Bordeaux, i., pp. 161, 163, 1854; Sphcerium solidum Nor- 



mand; Westerlund, Fauna Palaearct. reg., vii., p. 6, 1890. 

 ^>Eupera Bourguignat, Rev. et Mag. de Zool., 2me Ser., vi., pp. 84, 663, 675, 1854; 



Pisidium Moquinianum Bourg. ; Westerlund, Fauna Palaearct. reg., vii., p. 40, 1890. 

 ~^>Limosina Clessin, Mai. Blatt., xix., p. 160, 1872, Spharium bahiense Spix and 5". 



modioliforme Anton ; = Eupera Bourguignat. 

 ~^>Musculium Link, Beschr. Rostock Samml., p. 152, 1807 (Tellina lacustris Miiller, = 



Cyclas calyculata Drap.). 

 ~^>Calyculina Clessin, Mai. Blatt., xix., p. 159, 1872; Westerlund, Fauna Palaearct. reg., 



vii., pp. 5, 14, 1890 (= Musculium Link). 



A revision of this family with definitions of the proposed new subdivisions 

 was published in the " Proceedings of the Biological Society of Washington," 

 volume xvi., February, 1903. 



The genus Sphcsrium forms a very natural group, of which in America 

 none is known earlier than the Laramie, nor in Europe than the lower Eocene. 

 It is divisible into several well-marked groups. The hinge retains permanently 

 a condition of immaturity in the development of the teeth which recalls that 

 of the Leptonacea. The type is that of the Cyrenida, but the teeth cease de- 

 veloping before arriving at the stage corresponding to that of Corbiculina, 

 which is nearest to Spharium in its hinge characters. The edge of the mantle 

 is modified behind to form two delicate siphonal tubes, which, however, never 

 take on the muscular character of true siphons and are contractile rather than 

 retractile. The pallial line therefore exhibits no sinus. The sculpture is con- 

 centric and seldom strong. The beaks sometimes exhibit the nepionic stage 

 distinctly and sometimes not. The ligament is deep-set, in a groove whose 

 upper edges nearly meet over it, in species of the typical section; in others, 

 like 5. rivicola Leach, there is a wider gap in which the upper surface of the 

 ligament is visible. In none is the ligament absolutely occluded, and the dif- 

 ferences are small and only of degree. The cardinal teeth also are essentially 



