218 PROCEEDINGS OF THE NATIONAL \iisi:i \i. vol.38. 



These nebulae are Frequently blotched with white or the ground 

 color of the shell, and usually the nebulous color is intensified at the 

 anterior border of the blotch, as if the color glands, while the surface 

 of the white patch was being secreted by t he usual process, bad ceased 

 functioning temporarily, and begun again, with special intensity when 

 terminating the period of inaction. 



The second set of coloration features is produced by fine axial 

 lineation, the lines being usually dark in color. When they intersect 

 at right angles to the spiral banding they form tessellation; when 

 they develop zigzags and in the absence of distinct spiral bands we 

 have the coloration of light tent-like triangles, imposed upon the 

 ground color, as in the Textile group of cones. 



In the complex of color pattern the last factor comprises spiral 

 lines, often alternating Lighl and dark, or their continuity may be 

 so effectually interrupted that the dark parts are reduced to dots 

 and their relation to the spiral lineation be obscured. There 1 are also 

 pale and dark individuals where the lineation is lost entirely and no 

 nebulae occur, so that the relation of the individual to the species 

 must be deduced largely from the form and sculpture. 



Most cones have, near the canal, more or less spiral sculpture, and 

 in some species like C.arcuatus this sculpture may sometimes be con- 

 lined to the anterior part of the whorl and at other times may invade 

 the w hole lateral surface, reaching nearly or even quite to the shoulder. 

 Failure to realize this difference within the species is responsible for 

 some unnecessary names. 



The spire may he convex or concave, the fasciole between the shoul- 

 der and the suture may he swollen or excavated, smooth or spirally 

 striate. The shoulder may be rounded, carinate or even coronated 

 by a series of nodules. These characters arc 1 usually pretty constant 

 and may he relied upon for specific diagnosis. 



A recent attempt to revise the West American Cones in the National 

 collection and correct the nomenclature led to the preparation of the 

 following summary, which may he regarded as preliminary material 

 toward a future monograph. Some new forms are added to the 

 fauna and some species confused with others in the past have received 

 distinct iv name--. 



Family CONIMJ. 



Genus CON US LinnseLis. 

 CONUS FERGUSONI Sowerby, 1875. 



Magdalena Bay, Lower California, to Ecuador and the Gala- 

 pagos Clauds. 

 This white and rather rude species is the largest of the genus on 

 the wesl coast of America. 



