174 TURRITELLIDiE. 



than the other two. As is customary in the genus, tlie 

 strength and regularity of these carince cease upon the 

 larger coils, which are additionally furnished with costellar 

 strise. The suture is well marked, and the turns are 

 subangulately convex ; the upper shelve is decidedly the 

 longer and more slanting of the two. There is neither 

 imbrication, margination, nor channel-like excavation, as in 

 certain species of Turritellcc. The longitudinal increase of 

 the whorls is gradual but sensible ; they are almost as broad 

 above as below. The abrupt basal declination is rounded 

 towards the mouth, and the extreme base is often tinted 

 with vinous or dirty pink. The mouth is squarish, and 

 the more or less arcuated outer lip is subsinuated in the 

 middle. Our largest specimen measured nearly two inches 

 and three quarters in length, and three quarters of an 

 inch at the extreme breadth ; such dimensions, however, 

 are not usual, an average-sized individual (of seventeen 

 turns) being two inches in length, and half an inch in 

 breadth. Examples of the white variety are, for the most 

 part, smaller, more fragile, and with the spiral costel- 

 lar lines more minute in proportion to the carina;. 



The animal of this shell has a flattened emarginated or 

 cloven muzzle, with fimbriated edges ; its tentacula are 

 rather long, and at the external bases, on very slight 

 bulgings, are the immersed eyes. The foot is short and 

 strong, grooved below, angulated in front, and rounded 

 behind, where it bears on a simple caudal lobe the round 

 multispiral fringed operculum. The general hue of the 

 head, foot, and sides, is white, sometimes tinged with 

 tawny, and always more or less dotted and speckled with 

 fulvous and black. The tentacula are often tawny at their 

 bases, and yellowish above the eyes. The margin of the 

 mantle is fringed with minute tripinnated lobes, which are 



