among the Shetland Isles. 249 



that, under the circumstances I have mentioned, " there appears 

 to be a probability that these two species may occur somewhere 

 in the neighbourhood— if not quaternary; but if this last, I 

 hardly think they would have been so perfect and fresh as you 

 describe them to be." Professor Loven, who has examined my 

 specimens, considers them recent. According to Professor Sars, 

 R.psitfacea inhabits the coast of Finmark, as far south as Tromso 

 (69° 40' N. lat.), at depths of from 20 to 80 fathoms. Mr. 

 M^Audrew dredged it off Drontheim and in Upper Norway, at 

 depths of from 40 to 150 fathoms. Drontheim lies in 63° N. 

 lat., Unst in about 61°. 



Leda pernula, Miiller. 



A valve, apparently fossil, was dredged on the northern coast; 

 and several valves in a fresh state (partly covered with a glossy 

 epidermis) and a small perfect but dead specimen were dredged 

 in St. Magnus Bay, on the west coast, at a depth of from 60 

 to 80 fathoms. As no glacial fossils of ai'ctic kinds occurred on 

 the west coast, I have no hesitation in regarding L. pernula as 

 British. I had in former expeditions dredged small valves 

 and a complete pair east of Shetland and in the Hebrides. This 

 species inhabits the Scandinavian coasts, as far south as Kullen 

 in Sweden, from 20 to 150 fathoms; and M'Andrew records 

 a depth of 160 fathoms: it is widely diffused over the arctic 

 seas of both continents, and it is also one of our post-tertiary or 

 quaternary fossils. 



The next two species are especially interesting, in respect both 

 of novelty and of the classification of the Mollusca. They 

 belong to the class Solenoconchia (Solenoconchte, Sars, or 

 Scaphopoda, Bronn), which is represented by the genus Denta- 

 lium. I have elsewhere so fully treated of this I'emarkable class 

 that I will now offer merely a few remarks as to the genus 

 Siphonodentalium of Sars, to which or an allied genus the spe- 

 cies now about to be noticed must be referred. Siphonodentalium 

 (perhaps the type of a separate family of Solenoconchia) is dis- 

 tinguished from Dentalium by having an extensile worm-like 

 foot, the disk of which expands in the shape of a flower and is 

 furnished with a spike, by the mouth or anterior orifice of the 

 shell being obliquely truncated (in Dentalium it is circular), and 

 by the posterior or smaller orifice having its margin serrated or 

 slit on each side, instead of this orifice being furnished with a 

 short pipe or having its margin slit on one side only. I am 

 inclined to refer one of the species now discovered as British to 

 the genus Siphonodentalium, and the other to the genus Cndulus 

 of Professor Philippi*. In the latter genus (which Philippi 



* Moll. Sic. ii. p. 209. 

 Ann. ^ Mag. N. Hist. Ser. 3. Vol. xx. 1 7 



