348 TRANSACTIONS OF THE WAGNER FREE 



This is a more swollen and larger species than the preceding, and some- 

 what more frequent in its occurrence. The young show an obtuse peripheral 

 angle, but the last whorl of the completely adult shell is quite rounded. 



Family TRUNCATELLIDyE. 

 Genus TRUNOATELLA Risso. 



It is somewhat remarkable that this genus, which is widespread in its 

 present distribution in the Antilles and on our Southern coast, and which in 

 Europe is found in faunae of Eocene age, has not yet turned up from our Plio- 

 cene, to say nothing of earlier beds. I note this circumstance in order that 

 future collectors may bear it in mind and, if possible, either find it or confirm 

 its absence. 



Family CALYPTR^ID^. 

 Genus MITRULARIA Schumacher. 

 Calyptma Lamarck, iSoi, not of Lamarck, 1799. 



Mitnilaria equestris Linn^. 

 Mitrularia equestris (Linn^) Dall, Blake, Gastr., p. 283, 1889. 



Pliocene of the Caloosahatchie beds, rare, Dall ; living on the coast of 

 the United States from Cape Hatteras, N. C, southward to Florida, and in 

 the Antilles. 



Genus CRUCIBULUM Schumacher. 

 Section Criicibiilutn s. s. 



This section is distinguished from Dispotcea Say by having in the adult 

 the whole margin of the internal cup free from the shell, and the cup as a 

 whole merely attached by a narrow strip of adhesion ; while in Dispotcea a 

 third or half of the cup is formed by the wall of the shell. 



Both sections are remarkable for the modifications of external sculpture, 

 due largely to the irregularities of the surface upon which they rest, which 

 are reflected in the form of the margin of the base applied to them, but also 

 to modifications of the surface originated by the animal. The normal sculpt- 

 ure is of radiating riblets, coarse or fine, but these may have a microscopic 

 shagreening, or may be furnished with tubular spines, or small tubercles, all 

 within the species and often on different growth-stages of the same specimen. 



The group is known only from the Miocene and later horizons. A 

 C. antiquum, described by O. Meyer from the Claibornian, proved when cleaned 

 from the matrix to be a Balaniis. As originally constituted, Dispotaa was a 

 synonym of Criuibulum, but has been retained by Conrad, Morch and the 

 writer, for the species indicated above, in a sectional sense. The species of 

 both groups have been very greatly overstated by naturalists who have 

 assumed the constancy of the surface characters or those due to station. 



