502 ON THE FAUNA AND BOTTOM-DEPOSITS NEAR THE 30-FM. LINE 



iu fine mud in the interior of dead laiuellibranch shells, the valves 

 of which had remained together. 



Distribution. Geographical. Fiimuuk to Mediterranean and Canary Islands (JelFreys). 

 Kcrguelen Islands {Challenger, No. 107). 



DcjHh. Low-water to 800 fatlioms {Porcupine). 



Bottom-dcx>osit. Both Forbes and Haiiley, and Gwyn JefFreys mention the habit of this 

 species of living in the mud inside dead bivalves. Jeffreys also states that it is sometimes 

 found under stones at the lowest range of spring tides, sometimes in the excavations made 

 by other animals in rocks 



Modiola s]). Small specimens of Modiola, which I am inclined to 

 regard as young Modiola modiolus, were frequently taken attached 

 to shells and at the roots of Cellaria, hydroids, etc. Modiola harhata 

 has also been recorded. 



Micula nucleus. Two living specimens only were taken, one in haul 

 7G (Ground VIT.) and one in haul 103 (Ground XIII.). The former 

 haul (7G) is probably a mixed haul, first on fine gravel and then on 

 somewhat coarse sand. Haul 103 is on gravel mixed with a good 

 deal of mud. Empty shells were taken on Grounds VI., XIII., 

 and XIV. 



Distribution. Geographical. Lofoten Islands; British Coasts, etc., to Morocco and 

 the Mediterranean (Locard, No. 69). 



Depth. 3 fathoms (Jeffrej's) to 219 fathoms (No. 61, Caudan expedition). 



Bottom-deposit. Forbes and Hanley (No. 25) state that Nucula nucleus frequents coarse 

 bottoms (7-10 fathoms) and gravel, or muddy gravel to 90 fathoms. Forbes (No. 24, 

 Brit. Assoc, 1850) records it from gravel, from stony ground, from nullipores, from sand, 

 and occasionally from mud. Gwyn Jell'reys says it is conmion on sand and gravel. 

 Metzger (No. 77) records it on sand and shell, on mud and sand, on fine sand and 

 on mud. Heincke (No. 39) states that at Heligoland the species is very common on 

 fine muddy sand with shells and small stones, where it is associated with Vcniis ovata, 

 Cardium fasciatum, and Trochus tumidus. Petersen (No. 95) records it from mixed 

 deposits (nmddy sand and gravel). On the whole, therefore, we may conclude that 

 tlie natural home of the species is upon gravels and coarse sand mixed with mud. The 

 following species {N. nitldu) is found largely on fine sand as well as on coarser ground. 



Nucula niiida. This was only taken once, viz., on the outer 

 Eddystone Trawling Ground (II.) in haul 104. It was obtained in the 

 sample of fine sand brought up with canvas bag dredge. This explains 

 why it ■was not seen in the other hauls on Ground II. Several living 

 specimens were buried in the line sand (for the composition of this sand 

 see Table II.), and its shells were very numerous. 



Distribution. Geographical. Greenland, Norway, British Coasts to Mediterranean 

 (JellVeys, No. 55). 



Depth. Low tide-mark to 86 fatlioms (Jeffreys) ; to 100 fathoms (Hoyle, No. 52). 



Bottom-drposit. Forbes and Hanley state that the species occurs on sand in shallow water, 

 whilst Gwyn Jeffreys says only that it is found with Nucula nucleus, but is neither so gener- 

 ally diffused nor so plentiful. Forbes {Brit. Assoc, 1850), gives several records, the majority 

 (eight) being on coarse ground, whilst four are on sand or on sandy mud. Metzger 

 (No. 77) mentions it twice in the I'ommerania dredgings on grey calcareous mud and on 

 mud. Petersen (No. 95) saya that in tbr Ivattegat A'urula nitidu is never found on the 



