FROM THE EDDYSTONE GROUNDS TO START POINT. 469 



aud fine sand ground (Ground IX.) to the west of the Eddystone. One 

 or two specimens were generally taken on the fine gravel ground 

 (XIV.) between the ground last mentioned and the Eddystone rocks, 

 and several specimens were present on the gravel and mud ground 

 (XIIT.) south-east of the rocks. Single specimens were also met with on 

 Grounds VIII., VI., and IV., as well as on the Bolt and Prawle Grounds. 

 On the typical fine sand grounds (I., II., III., and V.) it was never met 

 with, nor was it ever taken on the gravel and sand grounds north-west 

 of the Eddystone (XL and XII.), its absence being specially noteworthy 

 in this case on account of the very close similarity in the composition 

 of the bottom-deposits, as shown by the figures in Table II. (p. 525), of 

 Ground Xl.with that of Ground IX., upon which the species was numerous. 



Habits. I kuow of no difference in the habits of this species and those of 0. ciliaris, witli 

 the exception of the fact stated by Forbes (Xo. 22, p. 28), that it is less active in confinement 

 than that species. Mbbius (No. 88, p. 143) observed this species coil its arms around a 

 living Nereis diversicolor and draw it into its mouth. 



Distribution. Geographical. Mubius and Biitschli (No. 88) give Norway, Kattegat, 

 \V. Baltic, British Seas, Faroe, W. France, and Mediterranean. Bell (No. 7) adds to 

 these the Arctic Ocean. Cams (No. 14) gives the Azores as one of the localities of the 

 species, and the same locality is mentioned by Greelf (No. 32). On the whole, therefore, 

 the range of 0. albida appears to be about the same as that of 0. ciliaris, with the 

 exception of the northerly extension of the former to the Arctic Ocean. Forbes (No. 22) 

 states that 0. albida is moi-e common than 0. ciliaris in British Seas, and this certainly 

 seems to be the case in the Irish Sea and in the North Sea. In the neighbourhood of 

 Plymouth, as already explained, quite the reverse is true, 0. albida being one of the rarer 

 ojjhiurids, and very much restricted in distribution. Had 0. albida been a distinctly 

 northern form and 0. ciliaris a southern one, it might have been supposed that the two 

 species overlapped in this district, aud that the southern form had almost but not com- 

 pletely replaced the northern one. The general distributions of the two species already 

 given, however, makes such an explanation impossible. In this connection Forbes' state- 

 ment, confirmed by Leslie and Herdman (No. 43), that 0. ciliaris is common at the mouth 

 of the Firth of Forth, whilst it becomes scarce and is replaced by 0. albida further up, is of 

 interest. 



Depth. Lyman (No. 71) gives the range from 5-250 fathoms, showing that the species 

 goes lower than 0. ciliaris, a fact which may be correlated with its extension to the Arctic 

 Ocean, and due to its adaptation to a lower temperature. 



Bottom-deposit. Forbes (No. 22) states that 0. albida frequents oyster-beds and sandy 

 places, and that it is more confined to the sand than 0. ciliaris. Mobius and Biitschli 

 (No. 88) record it in the North Sea generally from mud or sand, occasionally from gravel. 

 They state definitely that it is a mud-dweller (p. 146, note under Ophiocoma nigra). 

 Meissner and Collin (No. 76) record it also generallj' from fine sand or nuid, occasionally 

 from coarser ground. In the Kattegat Petersen (No. 95) took the species frequently on 

 sand and muddy sand, seldom on the pure mud. For the Irish Sea Chadwick (No. 15) 

 records it as plentiful with 0. ciliaris on a muddy bottom at 10 fathoms in the Menai 

 Straits. He also mentions it olf Port Erin on gravel and stones, and south of Isle of Alan 

 (10-20 fathoms) on nulli|iore and gravel. Haddon (No. 34) found it olf south-west coast of 

 Ireland, with 0. ciliaris, in 44-47 fathoms on luud. Hoyle (No. 52), on the other hand, 

 on the west coast of Scotland, took it in 34 fathoms with a number of smooth, rounded 

 pebbles, Ebnlia tuhcrosa — a sjiecies invariably founil on a coarse ground — being present in 

 the same haul. It would thus seem that 0. albida is found upon almost, if not quite, 

 as extensive a variety of bottom-deposits as 0. ciliaris, and its peculiar distribution in the 

 Plymouth district, where it is never taken on the fine sand and is continod to coarse 

 gi-ound, is the more difficult of explanation. 



