Whelks and Cone lets 2 5 i 



upon the excreta of other mollusks, the Pallid 

 Pyramid (0. ^^a/^icZa) being frequently found on 

 Pectens near the excretory outlet ; others are found 

 under clusters of mussels, on the opercula of other 

 gasteropods, and at the base of seaweeds. As in 

 the case of other parasitic mollusks the shell is 

 white or nearly so. Space will not allow of an 

 enumeration of the species in the body of the work, 

 but a list of the British species will be found in the 

 Appendix. Jeffreys included in the genus the species 

 often separated to form the genera Tiirhonilla and 

 Bulimella. The genus Turhonilla consists of a 

 dozen species distinguished by having the central 

 pillar straight (instead of curved as in Odostomia) 

 and in most cases without the tooth-like 

 projection. The shell, too, is more elongated, 

 and the whorls have ribs running across them, 

 as shown in the figure of the Staircase 

 Pyramid (T. scalar is). The six species com- 

 prised in the genus Eidir)iella agree with staircase 

 Turhonilla in the elongated shell with its 

 straight and seldom-toothed pillar, but it is in this 

 case free from ribs of any sort and is polished. 



The remaining families to be mentioned in this 

 chapter are grouped together under the name of 

 Rachiglossa, on account of an agreement in the 

 disposition of the teeth on the radula. Instead of 

 there being a large number in each row, there are 

 here only three; but each tooth has its front edge 

 broken into a number of long sharp points, varying 

 with each family. The proboscis is long, but can be 

 completely retracted. In the type family, Muircidce, 

 the radula is contained in the proboscis, and its 



