FIlOiM THE EDDYSTONE GROUNDS TO START I'OIKT. 503 



mud ("clay"), is occasionally met with on sand and mud, but that it prefers clean sand. 

 Heincke (Ko. 39) states that near Heligoland it is frequent on pure mud, or mud with a 

 little sand mixed, and that it only occasionally occurs with N. nucleiis. 



It must be admitted tiiat the above records are not ver}' consistent, and cannot be held 

 to afford much confirmation of the idea that N. nucleus is a coarse gi'ound species (gravel, 

 broken shell, nuUipores, etc.) whilst N. nitida prefers fine sand. 



Area tctragona. A few small specimens attached to shells, etc., on 

 the Bolt Head Shell Gravel (XVII.) and on the Prawle Stony Ground 

 (XVI II.). 



Distribution. Geogrcqjhical. Fiumark to Mediterranean, Azores and Canaries 

 (Jeffreys). 



Dcjdh. Shore to 450 fathoms {Challenger, No. 107) ; to 704 fathoms (Monaco expedi- 

 tion, No. 20). 



Bottom-deposit. Crevices of rocks and chinks of old shells (Forbes and Hanley). 



Pinna pectinata. Shells only of this species were obtained. Small 

 single valves were moderately frequent on the Eddystone Grounds. 



Distribution. Geographical. British Coasts to Mediterranean and Canaries. On 

 British Coasts it appears to be only common in tlie western portion of the English 

 Channel. 



Depth. Low spring tides to 320 fathoms {Porcupi')ie). 



Bottom-deposit. In muddy and sandy gravel (Jeffreys). According to Forbes and 

 Hanley, Montagu found the species in Salcombe Bay at low spring tides, sticking in the 

 gravel with the valves upright, the broader end about one inch above the surface. 



Pectunculus glycimeris. Chart XV. Both living specimens and shells 

 of this species were abundant on the Bolt Head Shell Gravel (Ground 

 XVII.) and on no other ground. One small living specimen was 

 obtained on the Prawle Stony Ground (XVIII.) in haul 29, and another 

 small one in haul 97 on the fine gravel (Ground XV.) east of the 

 Eddystone. Shells were occasionally taken on the gravels west of the 

 Eddystone (see Table VL), but they were never abundant. Tuhidava 

 cornucopiae is often found growing on the posterior end of living 

 examples of this bivalve (see p. 445). 



Distribution. Geographical. Lofoten Islands to Mediterranean, Madeira, and 

 Canaries. 



Depth. 7 fathoms (Jeffreys) to 250 fathoms {Pm-cupine). 



Bottom-deposit. Forbes and Hanley say of this species that it is gregarious and prefers 

 a nullipore bottom. Forbes (Brit. Assoc, 1850) gives records from sand, gravel, nullipores, 

 and mud and stones. Gwyn Jeffreys says it occurs on sandy and shelly gravel and on 

 nullipores. Pectunculus gbjciineris is not recorded by Metzger in the North Sea, nor by 

 Petersen in the Kattegat. In the Liverpool district it is recorded on nullipore ground 

 (No. 41, p. 319), on stones, sea-weeds, and dead shells (No. 41, p. 323), on shells, stones, 

 and echinoderm spines (No. 40, Vol. YIIL, p. 20), and on shells, sand, and gravel (No. 

 40, Vol. IX., p. 34). It is clearly very generally confined to coarse grounds. 



Lima Loscombii. Chart XV. This species was most numerous in 

 haul 10 on the clean shell gravel north-west of the Eddystone (Ground 

 XVI.), and several living specimens were taken in haul 4G on the 

 coarse gravel and sand of Ground XI. In both these hauls the shells 

 were also nuiiicious. Single living .specimens were taken in hauls Jj5 



