52 



Syn. Sei'pula heptagona, Morris, Catal. 66. Den- 

 taliuni elephantinum, Brander, W.pl. \.J\ 11. 



1 HIS curious Serpula in the young state, which is rare, 

 much resembles S. crassa (tab. .SO.), but is distinguished 

 by showing indications, first of two, and soon afterwards 

 of two more keels, besides the dorsal one, making with the 

 edges of the base in all seven angles ; it is also rougher 

 and more conical. The seven angles become equal upon 

 the free siiell. The operculum varies much in form, as 

 shown in the figures a. and b. 



Brander has confounded the free form of this Serpula 

 with Dentalium costahim (tab. 70. fig. 8.) under the name 

 of Dentaljwn clephantinum. 



Not uncommon at Barton. Tlie specimens figured are 

 in Mr. Edwards's collection; we have the same species also 

 from near Paris, sent to the late Mr. Sowerby by Mons. 

 Defrance. 



SERPULA avita. 



TAB. DCXXXV.— /g. 1. 



Spec. Char. Attached throughout, gradually en- 

 larging, variously curved, subcylindrical, with 

 an expanded base and a dorsal keel, which 

 forms a spine projecting over the aperture ; 

 lines of growth arched ; ^iS.^^Q. of the aperture 

 thin. 



Nearly related to the recent Serpula triqiictra {Fernulm, 

 Lam.), but differing in having a thinner keel and smoother 

 sides. 



Attached to a fragment of Iiioccravms in chalk. Pre- 

 sented by Mr. Sankey in 1819, who found it at Dover. 



