SUPPLEMENT. 195 



priate term than tentacula. The foot is trilobate in the 

 genus Dentalium only : in Siphonodentalium and Gadulus it is 

 dibble-shaped ; and when it has penetrated the sand or mud 

 to its full extent, its extremity expands and takes the shape 

 of a round shield or disk, so as to give the animal a fulcrum 

 and enable it to withdraw its shell in the same direction. 

 According to Mr. Jabez Hogg the odontophore of D. entalis is 

 a modification of that of the Chitonidce. In the Vidensk. 

 Forh. Christ, for 1858, Prof. Sars regarded this class as an 

 order of Acephala, calling it Solenoconchce. He does not refer 

 to the monograph of Prof. Lacaze-Duthiers, which was pub- 

 lished in the preceding year ; and it may be presumed that he 

 was not aware of it. It is a curious case of coincidence. 

 Prof. Bronn also distinguished Dentalium as the type of a sepa- 

 rate class, under the name of Prosopocephala or Scaphopoda. 



P. 188, 1. 16 from top, for " are bred " r. " issue ". 



P. 191. — Add Genus I. Sipho'nodenta'lium*, Sars. 



Body slender : captacida numerous : foot vermicular and 

 extensile, its extremity being capable of expanding into a disk 

 with a digitated margin and a central spike. 



Shell narrowly funnel-shaped or cylindrical, curved, thin, 

 obliquely but minutely striated in the line of growth, and 

 sometimes ribbed lengthwise : base having several notches. 



Siphonodentalium LoFOTEN'sEf, Sars. 



;S^. hfotense, Sars, Malacozoologische Jagttagelser in Vid. 

 Selsk. Porh. 1864, p. 17, t. vi. f. 29-33. 



Body transparent : captacida slender. 



Shell somewhat cylindrical, gradually tapering to a narrow 

 point, rather glossy and semitransparent : sculpture, fine, close- 

 set and slanting strioe, which constitute the lines of growth : 

 base having four slight equidistant notches. L. 0-2. B. 0-025. 



Habitat: Muddy sand in 40-140 f., among the Hebrides 

 and Shetland Isles. Xorway, 30-300 f. (Sars) ; G. Gascony, 

 60-80 f. (De Folin) !; Naples and Sicily, 50-60 f. (Acton and 

 others) ! 



The sheU differs from the young of Dentalium entalis in 

 being more curved and regularly tapering; the mouth and 



* Compounded from its tube-like shape and '■'Dentalium!' 

 t Originally found in the Loffoden Isles. 



k2 



