among the Shetland Isles. 253 
bella nana, Pleurotoma brachystoma, Cylichna acuminata, Philine 
quadrata, and P. nitida. 
3. Habits of Animals.—Species which were supposed to in- 
habit shallow water only were found living at considerable 
depths. In this category may be mentioned Natica catena, 
which was dredged alive in from 40 to 50 fathoms. Capt. 
Thomas informs me that he also dredged this species in the 
Orkneys living at the same depth. A dead specimen of Séilifer 
Turtont was procured with Natica catena. Bathymetrical con- 
ditions are not of so much consequence to the Mollusca as a 
suitable habitation and a good feeding-ground. We had the 
good fortune of dredging in 170 fathoms—a greater depth 
than had been previously explored in the British seas. This 
was about forty miles N.N.W. of Unst. The ground was 
stony intermixed with patches of sand. The greatest depth 
recorded as having been dredged in our seas was 145 fathoms, 
by Admiral Beechey, off the Mull of Galloway. The following 
is a list of the Mollusca which I examined from our dredging 
in 170 fathoms :— 
Livng.—Bracuiopopa: Terebratula cranium, young ; T. caput- 
serpentis, young; Crania anomala. CONCHIFERA: Anomia ephip- 
pium, young; A. patelliformis, var. striata; Lima subauriculata, 
young; Leda pygmea; Montacuta substriata, on Spatangus meri- 
dionalis? ; Venus ovata; Lucinopsis undata, young; Saxicava ru- 
gosa. SoxienoconcuHiaA: Dentalium entalis, var. anulata. Gas- 
TROPODA: Trochus occidentalis; Eulima bilineata; Natica Mon- 
tacuti ; Trophon Barvicensis. 
_ Dead.—Concuirera: Pecten septemradiatus, a fragment; P. 
tigrinus, ditto; P. similis, a single valve; Crenella decussata, frag- 
ments; Nucula nucleus, single valves; N. tenuis, ditto; Leda mt- 
_ nuta, a single valve; Limopsis aurita, small but fresh single valves; 
Arca pectunculoides, single valves ; Lucina borealis, perfect ; Axinus 
Croulinensis, single valves; Cardium fasciatum, ditto; C. minimum, 
ditto; Astarte sulcata, ditto; Venus lincta, ditto; Tellina balaus- 
tina, a fragment ; Psammobia Ferréensis, ditto; Mactra solida, var. 
elliptica, single valves; Scrobicularia prismatica, a fragment; 
Thracia papyracea, var. villosiuscula, young; Neera cuspidata, a 
fragment. Gastroropa: Teetura fulva, var. albula ; Propilidium 
ancyloides ; Emarginula fissura ; Trochus amabilis, young ; T. mille- 
granus, ditto; Turritella terebra, var. nivea; Natica Alderi; Tri- 
chotropis borealis ; Buccinopsis Dalei, a fragment ; Fusus gracilis, 
young; Ff. propinguus, ditto; Defrancia teres; D. linearis, var. 
@qualis, a fragment; Pleurotoma costata, ditto; Cylichna alba, 
ditto. Preropopa: Spirialis retroversus ; Clio or Cleodora cuspi- 
data, a fragment. 
Of these species sixteen were living, and thirty-eight dead— 
