LAMELLIBRANCHIATA. 



53 



6i°4o' — 7°4o' 135 fm. 1 spec, and I valve. 



6l V — 7°54' — 181 - Temp. 8.42 C. 1 



9 miles E. S. E. of Bispen ca. 70 - 3 valves. 



16 — E. by S. of south point of Nolso 80 - 4 spec, and 1 valve. 



Akralejte in N. 57W., 12 miles - 150 - 1 



13 miles W. by S. of Muaken - 150 - ca. 100 valves. 



At Iceland it reaches a length of 19 """. in the shallower waters, whilst the specimen from 

 691 fm. (St. 54) is only 3.5""". long- and the largest specimen from 316 fm. (St. 55) 7.5""". The largest 

 of the specimens at hand from the Faeroes is 16 """. long. 



Remarks. The numerous specimens to hand confirm in every respect the variation remarked 

 upon by other authors; the form of the shell is sometimes elongated, sometimes very short, but with 

 all transitions. 



Modiola phascolina is often confused with the young of M. modiolus, from which however it 

 can be distinguished with certainty by means of the following combination of characteristics (ef. PI. Ill, 

 figs. 2a— b (M.phaseolina) with figs. 1 a — b (M. modiolus, young): 



The shell is more ventricose. 



The anterior end tinder the umbo is less prominent. 



The inner edge of the antero-dorsal margin is finely crenulated across, and the hinge-margin 

 in from the beak is somewhat flattened and expanded and marked by minute transverse teeth. 



The impression of the anterior closing muscle is bounded above by a ridge-like projection from 

 the shell-margin. 



The antero-dorsal margin rises more steeply and the dorsal margin is for some distance almost 

 parallel with the ventral margin. 



Distribution. Modiola fhaseolina is distributed from northernmost Norway (Varanger Fjord) 

 along Europe and into the Mediterranean as far as the Aegean Sea; it goes down into the Kattegat. 

 To the west it reaches over the Faeroes to the south-eastern, southern and western coasts of Iceland. 

 • Jeffreys gives the vertical distribution to be from — 3000 fm., though it is not apparent where 

 he has obtained the record of this enormous depth from; the greatest depth noted by himself lies in 

 the Mediterranean at 14151111'). At Norway, according to G. O. Sars, it reaches down to 300 fm., at the 

 Faeroes and Iceland to 691 fm., so that I am inclined to doubt the correctness of Jeffreys' record. 

 Nor is the purely littoral occurrence quite certain, as it has not been taken living at less depths than 

 13 fm. at Iceland, the Foeroes, Norway or Denmark. That it may be washed up on land is anothei 

 matter; I have before me a number of apparently fresh shells, which had been washed up on the 

 beach at Heymaey, Vestmannaeyjar on South Iceland (collected by Dr. A. C. Johansen). 



Dacrydium vitreum M oiler. 

 Modiola.' vitrea "Holboll", Moller, Index Moll. Groenl., 1S42, p. 19. Dacrydium vitreum Torell, 



Spitsbergeus Molluskfauna, 1859, p. 139, PI. 1, fig.2; Sars, Moll. Reg. Arct Norv., [878, p. 28, 

 PI. 3, fig.2; Verrill, Transact. Connecticut Acad., V, 1882, p. 579, l'l. | |, fig. 8. 

 ■) Jeffreys, as usual, does not mention whether tin- shells were "dead"' or contained the animal. 



