74 



the TurritellidcB as proposed by Forbes and Hanley, or 

 adopting Gray's name of Ccecidce. The affinity of Caecum 

 to Vermetus is certainly very close, in respect not only 

 of the animal, but also of the shell and operculum. 



Genus CAECUM *, Fleming. PI. I. f. 6. 



BODY short. 



SHELL free, forming a curved and small cylinder, having in 

 an early stage of growth a loose but regular coil of whorls, 

 which afterwards falls off, the truncated extremity being then 

 closed by a plug : operculum solid. 



Costa would not believe the strange metamorphosis 

 which the shell undergoes ; but it is constant in every 

 species. Such similitude in dissimilitude teaches us, as 

 it did Charles Lamb, 



" That harmonies may be in things unlike." 



From Professor Stimpson's account of C. pulchel- 

 lum it would seem that a fresh truncation takes place 

 during each of the last three stages of growth, when a 

 separate plug or septum is formed. This genus is evi- 

 dently allied to Omalaxis or Bifrontia, in the convolution 

 of the spire and form of the operculum. Our knowledge 

 of the animal is entirely derived from Mr. Clark's excel- 

 lent observations. Mr. Alder says, as to the tongue of 

 C. trachea, " the lateral spines, in two longitudinal rows, 

 are slender and very numerous, with a minute plate in 

 the centre." The ' Proceedings of the Zoological So- 

 ciety of London ' for 1858 contain an elaborate mono- 

 graph on the recent Ccecida by Dr. P. Carpenter. Fossil 

 species occur in the Eocene and Pliocene strata of this 

 country and Italy. 



* A blind gut. 



