the type of the Genus Ditntpa. 425 



that any were alive when taken, it became a matter of interest if possible 

 to procure further information establishing the claim of the species to a 

 place in the list of our marine animals: and I was the more anxious, as an 

 examination of Mr. Lowe's specimens had convinced me that it was not a 

 Dentalium, but formed a new genus among the Annelida. Accordingly, 

 wben in the following summer the survey of the bank was resumed, I 

 requested Captain Vidal to preserve for me in spirits whatever animals he 

 should procure alive in sounding; and if possible specimens of the Den- 

 talimn. This he very kindly undertook and noted the depth at which each 

 specimen was taken. Tlie Dentalium did not occur at any less depth than 

 63| fathoms, and twice (on one occasion ofif St. Kilda) it occurred at 

 171 * fathoms. Nothing could be concluded as to habit from the man- 

 ner in which the shells were imbedded in the tallow, but this was of the 

 less consequence as from information received from Mr. Lowe it appears 

 that they are found in great numbers together, in masses of a conglome- 

 rate (if it may be so called) of mud and various marine substances, the 

 broader end only appearing above the surface. From the amazing dif- 

 ference in the diameter, it should seem that the narrow or posterior end 

 is gradually absorbed in the course of growth. The animals of the 

 Madeira and British specimens, as was supposed, proved perfectly 

 identical. 



It will clearly appear from the description and accompanying fio-ure 

 that notwithstanding the resemblance of the shell to that of true Den- 

 ialia, it is most nearly allied to Serpula; but evidently distinct in having 

 an unattached shell (for there is no evidence to lead to a suspicion that it 

 isattaclied, even in infancy), and more especially in possessing a poste- 

 rior as well as anterior aperture. I have therefore no hesitation in 

 proposing a new genus Dilrupa (ac and r^vn-r] foramen) for the recep- 

 tion of this and such other species now included in Dentalium, as shall 

 be found to possess an animal similarly organized. One at least is so 

 circumstanced, DentaHumGadus, Mont. {Dent.coarctatum, Lam,),ofthe 



* A specimen of Crania pcrsonata was taken a( tlie ininicnse depth of 

 255 fathoms. 



