CADULUS-POLYSCHIDES. 153 



This species does not attain the dimensions of C. speetabilis, and 

 it differs from the tetraschistus group in being decidedly inflated. 

 The aperture is formed as in tetraschistus. 



Specimens in rather poor condition from Vera Cruz, Mexico, are 

 amall, length 7'5 mill., but we do not doubt their specific identity 

 with the Carolinian examples, some of which are under 8 mill. long. 



Var. BusHii Dall. PI. 33, figs. 58, 59. 



Shell resembling C. carolinensis, but somewhat smaller, more 

 abruptly constricted behind the swollen portion, and with the 

 posterior orifice a little smaller. Length 65; max. diam., 1.'25 

 mill. 



Barbados, in 100 fms. (Blake.) 



Cadulus (carolinensis var. ?) Bushii Dall, ' Blake ' Gastr. and 

 Scaph., p. 430, 1889. 



In the present uncertainty as to what constitutes a species in this 

 group, or what is the range of specific variation, it is impossible to 

 say whether this form should be regarded as a s[)ecies, or as a 

 variety of C. carolinensis Bush. (Dall.) 



The figures are from camera lucida sketches kindly furnished by 

 Dall. 



C sPECTABiLis Verrill. PI. 25, fig. 64. 



Shell very large for the genus, rather strongly curved, especially 

 behind the middle, swollen and somewhat angular and gibbous a 

 short distance back of the aperture. The gibbosity or swelling 

 affects most the dorsal side, but is distinct also on the sides and 

 ventrally ; in advance of this swollen part the shell narrows rapidly 

 to the aperture, the decrease being much the greatest on the dorsal 

 side. The aperture is oblique and elliptical in outline, the dorsal 

 margin being distinctly flattened. From the anterior swelling the 

 shell tapers regularly and gradually backward, with an increasing 

 curvature. The posterior opening is not very large, a little flat- 

 tened, and its margin, when perfect, has a moderately deep notch 

 on each side and a shallower one both above and below. The shell 

 is translucent and the surface is everywhere smooth and polished, 

 but shows irregular alternating bands of lighter and darker shade, 

 due to greater or less transparency of the substance, and there are 

 also faint longitudinal whitish lines visible in the substance of the 

 shell, but not affecting the surface (Verrill). 



