406 TRANSACTIONS OF THE WAGNER FREE 



(MSS. ?), C. corbis Dall and C. sapiduni Dall, the two latter being also known 

 living from deep water in the Antillean region, dredged by the Blake Expedi- 

 tion. 



Genus MARGARITA Leach. 



This genus extends from the upper Cretaceous to the recent fauna. The 

 shells are somewhat variable in their ornamentation, and may be umbilicated 

 or not, but the umbilical carina, if it exists, is not beaded or tubercular. Shells 

 of this general form, but with the carina annulate or beaded, are distinguished 

 in the recent fauna by marked anatomical differences from Margarita proper, 

 and from the genus Solariella S. Wood or Machceroplax Friele. We are 

 therefore justified in separating the fossils by the purely conchological 

 character. 



Meek has proposed a genus Margaritellaior 2.v\. upper Cretaceous species 

 with a sharp periphery, scalar umbilicus with uncrenate carina, and the pearly 

 shell of Margarita. 



Fischer, on the ground that the name had already been used for the pearl 

 oyster, proposes to name the genus Eiimargarita — a course which I do not 

 think required by the circumstances; but if we must give up the name 

 Margarita on this trivial ground, the name of Margarites proposed by Leach 

 himself has priority. 



Margarita tampaensis n. s. 

 Plate i8, figure 5. 



Older Miocene of the Orthaulax bed, Ballast Point, Tampa Bay, Florida, 

 Dall and Burns. 



Shell small, thin, of much the form and size of Margarita helicina, but 

 with the earlier whorls alternately striate, the striae becoming finer and at last 

 obsolete on the terminal whorl ; suture distinct, whorls rounded above and 

 below; umbilicus small, funicular, aperture expanded, oblique; body with a 

 thin callus. Alt. 7.0 ; max. diam. 8.0 mm. 



The striation on the different specimens varies as in recent species, some 

 having it perceptible though weak on the last whorl, especially below. 



Genus SOLARIELLA S. Wood. 



Solariella S. Wood, Ann. Mag. N. Hist. ix. p. 531, 1842. 

 Solariorbis sp. Conrad, Am. Journ. Conch, i p. 30, 1865. 

 Machcsroplax Friele, Arch. Math. Nat. ii. p. 311, 1877. 

 Solarium sp. Lea, Conrad, De Gregorio, etc.; not of Lamarck. 



The typical species of this group are somewhat widely umbilicated, but 

 there are other species which are imperforate, yet by the totality of their 

 characters evidently belong to the same assemblage. We know that in 

 Margarita the presence or absence of an umbilicus is hardly a specific charac- 

 ter, and in the section Bathymophila the young are widely umbilicate and the 



