TRANSACTIONS OF WAGNER 

 I 174 



TERTIARY FAUNA OF FLORIDA 



Montacuta sagrinata n. sp. 

 PLATE 44, FIGURE 6. 



Miocene of York River, Virginia ; Harris. 



Shell small, rounded, subequilateral, moderately inflated, thin, sculptured 

 with incremental lines and fine broken concentric ridges more or less irregular 

 and sometimes almost granular, with an obscure vertical constriction from the 

 beaks (which may be an individual feature) ; posterior end higher and more 

 rounded, anterior end more pointed ; a single small, projecting short lamina in 

 front of the beaks in the right valve with a rather long oblique sulcus for the 

 resilium behind ; interior mostly smooth or radially striate. Lon. 7.5, alt. 6.0, 

 diam. 3.75 mm. A second broken valve was proportionally a good deal more 

 elongate. 



This species at first sight recalled Aligena lineata, which has an extremely 

 similar surface, but the gap between the resilium and the tooth is less marked 

 and the aspect of the shell is decidedly more like Montacuta than Aligena. If 

 it belongs to the latter genus it is certainly not one of the described species. 

 The beaks are decidedly lower and the shell in front of them less impressed 

 than in any of the numerous specimens of Aligena I have examined. 



Montacuta (Orobitella) floridana Dall. 

 Montacuta floridana Dall, Proc. U. S. Nat. Mus., xxi., 1899, p. 893, pi. 87, fig. 10. 



Pliocene of the Caloosahatchie beds, Florida ; Pleistocene of North Creek, 

 near Osprey, Florida, Dall ; living on the coast of West Florida, Simpson. 



Shell subovate, inequilateral, posterior end shorter, white, inflated ; beaks 

 low, polished ; sculpture of concentric lines growing gradually stronger down- 

 ward and forward until on the lower anterior third they form low, stout, evenly 

 distributed, concentrically striated lamellae, while remaining feebler on the 

 posterior part of the shell ; base nearly straight, dorsal margin arcuated, ends 

 evenly rounded ; hinge with a prominent slender cardinal in each valve, the 

 laminae obsolete ; sockets of the resilium thickened and raised above the inner 

 surface of the valve. Lon. 16, alt. 10, diam. 9.5 mm. 



This is probably the largest species of the genus and the anterior laminae 

 have entirely vanished. There is no radial sculpture visible, but under strong 

 magnification a few fine striations can be made out on the anterior slope, which 

 are faintly reflected on the inner anterior margin. 



A broken valve of a species not unlike M. floridana, but less rounded and 

 inflated, was obtained by Harris from the Miocene of the York River, Virginia, 

 but it is too imperfect for description. 



