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 Lovén, who has examined my 
specimens, considers them recent. According to Professor Sars, 
R. psitiacea inhabits the coast of Finmark, as far south as Troms6 
(69° 40’ N. lat.), at depths of from 20 to 80 fathoms. Mr. 
M‘Andrew 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, Miller. 
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 arctic 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 (Solenoconche, Sars, or 
Scaphopoda, Bronn), which is represented by the genus Denta- 
lium. I have elsewhere so fully treated of this remarkable 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. Szphonodentalium 
(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 havifg 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. Iam 
inclined to refer one of the species now discovered as British to 
the genus Siphonodentalium, and the other to the genus Cadulus 
of Professor Philippi*. In the latter genus (which Philippi 
* Moll. Sie. ii. p. 209. 
Ann. & Mag. N. Hist. Ser. 3. Vol. xx. 17 
