FROM THE EDDYSTONE GKOUNDS TO START POINT. 505 



described in the present report P. ghjcimeris was only numerous on the Bolt Head shell 

 gravel, and on this ground P. maximus was never taken. The above records show that 

 Peclen vmxiynus is generally found on coarse gi'ound, especially where there is a consiiler- 

 able admixture of mud. 



Pecten operciilaris. Chart XIV. This, as is well known, is a gre- 

 garious species often occurring in large shoals or flocks. These shoals 

 are often of comparatively limited size, so that two hauls near together, 

 and taken on what have been regarded as the same ground, have differed 

 very much in the number of P. opercularis captured. The species was 

 taken in larger or smaller numbers on each of the eighteen grounds into 

 which the district examined has been divided, and Chart XIV. indicates 

 roughly the relative frequency upon the different grounds. The species 

 is most numerous on the Eddystone gravels and on the sand imme- 

 diately outside these. The largest beds occurred on Grounds IV., IX., 

 and XIV. On the fine sand of the outer trawling ground (Ground II.) 

 many specimens were captured in one haul only, viz., haul 24. On the 

 Bolt shell gravel and on the Prawle Stony Ground P. opercularis was 

 never numerous, and was generally not taken at all. 



On all the Eddystone Grounds young Pecten opercularis from about 

 O'o mm. breadth were abundant, attached to hydroids (especially 

 Halecium halecinum and SertulareUa Gayi), wherever these were 

 common, both on gravel and on fine sand bottoms. 



Distribution. Geographical. Norway to Mediterranean, Azores, Madeira, and Canaries 

 (Locard, No. 69). 



Depth. 5 fathoms (Forbes and Hanley) to 1457 fathoms {Porcupine). 



Bottom-dcp)Osit. Tlie records, which are fairlj' numerous for this species, indicate that 

 the mollusc may occur on both coarse and fiue bottoms, on gravel, on sand, or on mud. 

 In the Kattegat Petersen (No. 95) found P. opercularis chiefly on the mixed deposits and 

 not on the pure nmd. On the latter P. radiatus was the frequent species. 



Pecten tigrinus (Table VI.). Living specimens of this species were 

 not abundant, one or two in a haul being the largest number taken. 

 Shells also were not very numerous. The living specimens were for the 

 most part taken on coarse ground. 



Dlstkibution. Geogra^^hiad. Iceland, Scandinavia, British Seas to Vigo Bay (Jellreys, 

 No. 55). 



Depth. 7 fathoms (Jeffreys) to 106 fathoms {Pommcrania, No. 77). 



Bottom-deposit. Forbes and Hanley state tiiat tlie species is found on shells, gravel, and 

 sandy mud. Forbes (No. 24, Pril. ytssoc, 1850) gives seven records on niillijiore, on 

 gravel, or on shell, three on sand, one on sandy mud, and one on mud. Gywn Jeffreys 

 says that the species is found on a sandy bottom mixed with gravel. Mctzgcr (No. 77) 

 records it three times on stony ground, once on sand, and once on nuul. Petersen (No. 95) 

 found Pecten tigrimis (living) in the Kattegat three times on gravel or shell, five times on 

 sand and mud, and once on nuid. In the Liverpool district it is recorded on shell and 

 gravel (No. 40, Vol. IX., p. 33). The species may be found on either gravel, on samly 

 mud, or on mud, and its distribution seems to be littlo influenced by the nature of the 

 deposit. 



Anomia epkippinvi and Anomin patelliformis. Tiiese two species are 



found nil nil groiuKl^ where they can iiiid suitable places of atLacliinent. 



