TRANSACTIONS OF WAGNER 

 I I 66 



TERTIARY FAUNA OF FLORIDA 



The type of this genus well illustrates the slipshod methods, or want of 

 method, of Conrad. His first nude mention of the genus and species occurs 

 in his list on page lo, where the species is called parva, though the generic name 

 is masculine, but neither genus nor species is defined or figured. Subsequently, 

 at the place where the genus and species are described (p. 138), the latter is 

 called niinuta instead of parva and, with all the other species described in the 

 article, is said to come from Enterprise, Mississippi, though Dr. Spillman in- 

 formed the Hon. T. H. Aldrich that he had not sent Conrad any fossils from 

 Enterprise, but did send him some from the Jacksonian beds of Garland's 

 Creek in Clarke County, whence these fossils are doubtless derived. As the 

 name parva was never defined, it appears that iiiiiiutus will be the first valid 

 name applied to the type of this genus. This is misspelled inimatur in the 

 synonymy of the species given by De Gregorio (Mon. Claib., p. 210). 



This genus is closely related to Lutetia Deshayes, and they have been united 

 by Cossmann, but a prolonged study leads me to a different conclusion. The 

 differential characters are as follows : 



Lutetia Deshayes : Hinge with a well-marked nymph for an external liga- 

 ment ; right valve with three laminae, a posterior straight one nearly parallel 

 with the hinge-margin, in front of which is a larger one bent at an obtuse angle 

 just below the beak; and, lastly, a small tubercle immediately under the angle 

 of the last. Between the posterior tooth and the nymph the hinge-plate is flat 

 with no indication of an internal resilium in either valve. The left valve also 

 has three teeth, a straight anterior and posterior lamina radiating from the 

 beak, and between and below them a short lamina obtusely angular in the 

 middle. 



Alveinus Conrad: Hinge with a very feeble nymph only noticeable on the 

 largest and most fully developed specimens, and under the beaks a deep, well- 

 marked pit for an internal resilium. Right valve with two teeth, parallel with 

 each other and with the hinge-line, proximally elevated and with the upper 

 edges bent over and towards each other. Left valve with a single tooth bent 

 like a figure seven, the proximal arm shorter and with a small projection or 

 angular thickening on the ventral side at about the middle ; above this tooth 

 the subumbonal margin is sometimes thickened, with a groove between it and 

 the lamina. The posterior shell margin for about a third of the circumference 

 is prominent and is received in a groove in the corresponding margin of 

 the right valve. This grooving is occasionally continued nearly round the 

 shell both in Lutetia and Alveinus, at other times the margin is flattened or 

 simple. 



