FAUNA OF THE OUTER WESTERN AREA OF THE CHANNEL. 297 



in the Sound, was obtained only at 31 and 39 miles, in contrast to 

 P. robusta, which occurred fairly commonly over the whole area. 



FicuHna Jicns, though of common occurrence as far as 40 miles out, 

 was always of remarkably small size — much more so than it often 

 occurs on the Eddystone Grounds. This reduction of growth, as con- 

 trasted with the comparatively enormous size it often attains within 

 the breakwater, is no doubt attributable to the diminution of waste 

 organic matter on the distant grounds. 



Suberites carnosus, comparatively common on the Eddystone, Grounds 

 was only twice found, at 17 and 22 miles respectively. These also 

 were extremely small specimens. 



Hydromedusae. Except at the first few positions, on the fine sand 

 about 8 miles distant, and again at the outermost point reached, where 

 in 51 fathoms two -southern species showed a healthy luxuriant 

 growth, the examples recorded were on the whole remarkalily small, 

 and the occurrence of well-grown colonies was quite exceptional. In 

 the same connection the dwarfed form of Plumularia sctacea at two 

 outer positions in about 50 fathoms is remarkable. 



Mcrona cornucopiac was taken as far as 31 miles distant, which was 

 10 miles beyond the outermost record of its common associate Dentalmm 

 cntalis. 



Hydradinia echinata was only taken at 31 miles. 



Tuhularia was only recorded at the first position, 8 miles distant. 



Halecium halccinuin was not recorded outside about the 3-4-mile 

 point. 



A fragment only of Thuinria articulata was taken at 18 miles. 



Antennularia ramosa, though occurring as far out as 40 miles, was 

 not found common anywhere. The allied species, A. antennina was 

 common over the whole area. 



Phtmularia catharina was the commonest of its genus obtained, 

 P. pinnata alone approximating to it appreciably in point of fre- 

 quency. The creeping variety, which occurred over the whole area, 

 veas perhaps the most frequent and certainly the most flourishing in 

 point of growth. It is difficult to assign a cause for this mode of 

 growth. A colony of Bougainvillia, reared by Mr. E. T. Browne at 

 the Plymouth Laboratory some years ago (cf. Jowrn. Mar. Biol. Assoc, 

 aST.S., Vol. VIII, p. 37) assumed a persistent stoloniferous habit of 

 growth from the first. It was fed with mixed plankton regularly and 

 grew rapidly, but in^the several months of its existence, except in very 

 rare cases, it made^no attempt to assume the ordinary branching habit, 

 even though it ultimately succumbed to an overgrowth of small algae. 

 This single instance affords no evidence that food-supply alone in- 



XEW .SERIES. — VOL. IX. NO.* 3. .1X7NE, 1912. U 



