INSTITUTE OF SCIENCE, PHILADELPHIA. 147 



anterior face of the last varix as elevated ridges crossed by sharp incremental 

 lines and not as grooves, as in the more modern species ; there are three ribs 

 in front and four behind between the varices ; canal not long, slightly re- 

 curved ; aperture elongate, pointed before and behind ; inner lip elevated, with 

 a smooth edge, the surface slightly granulated in old specimens ; body cal- 

 lous, with a subsutural ridge ; outer lip with six teeth in front of the shoulder- 

 angle ; whorls rather full, appressed to the suture and undulated by it, rising 

 at the varices, somewhat constricted in front of the suture, the excavation 

 extending to the shoulder; spire rather short; early whorls smoother, with 

 the ribs more prominent. Max. Ion. of shell 29.0 ; of aperture and canal 

 20.0; max. lat. of shell 14.5 ; of aperture 5.5 mm. 



Fossil in the upper bed at Alum Bluff, Florida, and (var. intermedia) very 

 rare in the Caloosahatchie Pliocene. 



This form is immediately distinguishable from the more modern ones by 

 its smoother surface, less prominent varices, and especially by the way in 

 which the whorl is constricted and appressed in front of the suture, which is 

 thus made less even and less obvious. The fine secondary striation and the 

 absence of any sharp edges are notable features. 



There is a marked change between the Miocene form and its representa- 

 tive in the Caloosahatchie Pliocene. The high, appressed, smooth shoulder is 

 shorter, and its slope at a greater angle with the axis. There are no sharp 

 edges, and the specimens I have seen practically have but one varix. The spirals 

 are more numerous and the secondary ones coarser ; the transverse ribs more 

 numerous; reaching ten beside the varix. The shell is almost exactly inter- 

 mediate between the Miocene species and the true caudata of the more north- 

 ern Pliocene and recent fauna. For this variety I propose the name of 

 intermedia. 



Simultaneously with the above modification of the ancient stock, we find 

 the present southern variety sidcidentata present in the marls ; so the condition 

 which in intermedia preserved the rounded sculpture, was not unfavorable to 

 the development of sharp laminae in others. Perhaps the difference was really 

 one of local habitat, as we find at present between the smoother and the spi- 

 nose Melongena — a surmise which the condition of the marl-beds does not 

 permit us to verify or reject by observation. 



Genus UROSALPINX Stimpson. 



As Eiipleiwa resembles a Pteronotus with irregular and finally opposite 

 varices, so Urosalpinx may be compared to a Eiipleura in which the varices 

 have become obscure or absent. The other differences are not of great im- 

 portance. Urosalpinx tampaensis has been regarded as an aberrant Enplenra 

 by more than one good conchologist. 



The initiation of this group is not yet definitely determined. Fiisus pearl- 

 ensis and Pisania dubia Aldrich of the Upper Eocene have much the aspect of 

 this group. Murex simplex var. aspinosa (sic) Meyer is not a Murex, has no 



