TRANSACTIONS OF WAGNER 

 890 



TERTIARY FAUNA OF FLORIDA 



fragile, overhanging the pit almost in the plane of the valve margins, floor- 

 like ; there are two short but distinct, low posterior laminse but no anterior 

 dorsal lamina ; the scar of the retractor of the foot nearly marginal behind the 

 adductor. 



One recent species, the type, is known from the Straits of Magellan 

 (Gregory Bay, U. S. Fish Com.), and another has been reported from the 

 Straits of Fuca {D. dcclivis Cpr.) ; but the latter may be a Patagonian speci- 

 men with erroneous locality. 



The genera Cardilia and Anatinclla I have not had a sufficient opportu- 

 nity of studying. Their pertinence to this family is, to say the least, not yet 

 assured. The former I have not examined. The following notes were taken 

 from Anatinclla dilatata Rve. It should be mentioned that while H. and A. 

 Adams correctly figure the hinge of this genus, their description of it as con- 

 taining " two small teeth on each side in the right valve" is erroneous. 



? Subfamily ANATINELLIN.E. 

 Genus ANATINELLA Sowerby,iS34. 



Shell thin, porcellanous, finely radiated externally, with low adjacent 

 beaks, posterior gape well marked ; chondrophore large, narrow, projecting 

 obliquely backward; resilium large, narrow, with calcareous median layer; 

 ligament short, sunken, submarginal, strong ; left cardinal narrow, the poste- 

 rior arm wider below, long, strong, with a low accessory lamella between it 

 and the margin of the pit; anterior arm short; right cardinal short, small, 

 distinctly deltoid, with long, high accessory lamina walling the pit; lateral 

 teeth entirely absent ; paUial line somewhat irregular, but without any sinus. 



It is somewhat doubtful whether there is more than one species of 

 Anatiuella, — the A. nicobarica Gmelin or Sibbaldii Sowerby. The nominal 

 species are Indo-Pacific in distribution. Gray, in 1853, erected a family on 

 this problematical shell. It has a good deal the aspect of Tugonia, but the 

 hinges are not comparable. * 



There are some curious parallelisms in the characters of the different 

 groups above mentioned. They cannot all be tabulated in one scheme, but 

 offer some points worthy of investigation. 



The order of modification, theoretically, after the submergence and 

 division of the original Hgament into ligament and resilium, should have 

 followed two lines, one in which the parts, though separated, are not walled 

 apart by a shelly septum and the process of modification is still left unlimited 



