ON DREDGING AMONG THE SHETLAND ISLES. 435 



Macandrece, Cerithlojwis costulata, Bvccinitni Humplireysianian, Colnmhelht 

 wtna, Plenrotoma hrachtjstoma, Cijlichna acuminata, Pldline qiiadrafa, and P. 

 nitlda. 



3. Habits of Animals. Species whicli were supposed to inhabit shallow 

 Avater ouly were found living at considerable depths. In this category may 

 be mentioned JSrUica catena, which was dredged alive in from 40 to 5U fathoms. 

 Capt. Thomas informs me that he also dredged this species in the Orkuejs Hving 

 at the same depth. A dead specimen of iStdifer Tartoiu was procured with 

 Natica catena. Bathymetrical conditions are not of so much couseriuence to 

 the Mollusca as a suitable habitation and a good feeding-ground. Wc 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 TJust. The grormd was stony intermixed with patches of sand. The greatest 

 depth recorded as having been dredged in our seas was 145 fathoms, by Admi- 

 ral Beechey, oif the Mull of GaUoway. The following is a list of the Mollusca 

 which I examined from om- dredging in 170 fathoms : — 



Living. — Beachiopoda : Terebratida cranium, young; T. cujjut-serijentis, 

 young ; Crania anomula. Conchifeea : Anomia ephippium, young ; A. patel- 

 liformis, var. striata ; Lima suhauriculata, young; Leda pugma^a ; Montacuta 

 srdjstriata, on h^patancjus meridionalis ; Venus ovata ; Lucinopisis vndata, 

 young; Sa.vicava rugosa. Solenoconchia : Beniallum entalis, var. amdata. 

 Gastropoda : Trochus occidentalis; Eulima bilineata; Natica Montacuti; Tro- 

 plion Barvicensis. 



Dead. — Conchifeea : Pecten septemradiedus, a fragment ; P. tigrinus, ditto ; 

 P. sinulis, a single valve ; C'renella decussaia, fragments ; Nucula nucleus, single 

 valves; N. tenuis, ditto; Leda minuta, a single valve; Limopsis aurita, small 

 but fresh single valves; Area pectunculoides, single valves; Lucina borealis, 

 perfect; A.vinus Croulinensis, single valves; Cardium fasciatitm, ditto; C 

 minimum, ditto; Astarte sidcata, ditto; Venus lincta, ditto; Tellina bcdaus- 

 tina, a fragment ; Psammobia Ferroensis, ditto ; Mactra solida, var. elliptica, 

 single valves ; Scrobicxdaria prismatica, i^ fragment; Thracia papyvacea, var, 

 villosiuscula, young ; JVecera cusiyidata, a fragment. Gastropoda : Tectura 

 fulva, Yar.cdbula; Propilidium ancyloides ; Emarginidajissura; Trochus ania- 

 bilis, young; T. millegranus, ditto; Turritella terebra, var. nivea; Natica 

 Alderi; Trichotropis borecdis; Buccinopsis Dalei, a fragment; Fustis gracilis, 

 yoimg ; F. p)ropinc[uus, ditto ; Defrancia teres; D. linearis, var. eequalis, a 

 fragment; Pleurotoma costata, ditto; Cyliclina alba, ditto. Pteeopoda : 

 fSjiiricdis retroversus ; Clio or Cleodorapyramidata, a fragment. 



Of these species sixteen were living, and thirty-eight dead — in all, fifty- 

 four. They comprised some rarities, viz. Terebratula cranium, Limopsis aurita, 

 Axinus Croulinensis, Trochus amabilis, Buccinopsis Dcdei, and Cyliclina alba. 

 The shells were of the usual colour ; indeed this was brighter and darker in 

 living specimens of Venus ovata and Eulima bilineata than in average examples 

 of the same species taken in a few fathoms. The notion that colour is absent 

 or fainter in shells from deep water seems to be quite ixnfounded. 



4. Geological Relations. — Fossil shells (being apparently relics of the glacial 

 epoch) occurred in 170fathoms,and higher up to 80 fathoms. They were chiefly 

 Pecten Islandicus, Tellina calcaria, Mya trimccda, var. Uddevallensis, Saxicava 

 rugosa, var. Uddevallensis, Mblleria costulata, and Trochus cinereus. All these 

 species and varieties inhabit high northern latitudes, and none of them have 

 been discovered li^-ing in our seas. No sirch fossils were detected on any part 

 of the western coast of Shetland. 



5. Extrancotis incidents.— In the dredged stuff taken from a depth of about 



2 a2 



