THE NAUTILUS. 103 



color it is unevenly blotched white and horn color, a few ex- 

 amples opaquely white. When blotched or mottled, the cords 

 and growth wrinkles are often white, thus intensifying the con- 

 trast between the two colors. Spire elevated, whorls depressed 

 and sharply carinated. Spiral cords from 5 to 9, with two 

 strong cords or one strong cord between two smaller cords, above 

 the periphery. Fine spiral striae between cords, strongest on 

 the under surface. Growth wrinkles strong, 2 to 6 per mm., a 

 large wrinkle about every one and one-half mm. gives the under 

 surface a checkered effect. Whorls 4, umbilicus small, funnel- 

 shaped, not cylindrical, all whorls visible to the apex. Embryo 

 whorls 2, darker-colored, smoother than later whorls but 

 plainlv marked by spiral cords and oblique growth wrinkles. 

 Mouth oblique, and in older individuals lip sometimes stained 

 yellow. In the aged the last whorl often drops half below the 

 periphery. 



Alt. 10, diam. 17.5 mm. (No. 112918a, A. N. S. P.) 

 " 11, " 18 mm. 



Type specimens in my own collection and in the Academy of 

 Natural Sciences of Philadelphia. 



These shells had an enemy which broke an irregular hole in 

 the upper surface of the shell, about 2 mm. in diameter. I 

 have not noticed this form of destruction in other colonies of 

 land shells. 



THE NATUEE OF THE CONICAL BODIES ON THE MANTLE OF CERTAIN 



NUDIBRANCHS. 



BY W. J. CROZIER. 



Contributions from the Bermuda Biological Station for Research, No. 57. 



A study of the supposed "warning" coloration of brilliantly 

 pigmented nudibranchs as represented by Chromodoris zebra 

 Heilprin, has incidentally made clear the previously unknown 

 significance of the " white conical bodies" which occur on the 

 posterior ventral surface of the mantle of this species and give 

 it a beaded appearance. Since white nodular structures of a 

 presumably similar character have been noted upon the mantle 



