DISTRIBUTION OP CERTAIN BRITISH ALG^ 39 



though a slight growth of Geranium acanthonotum, which is often 

 a co-dominant species in the association, was present ; Nemalion 

 also, which enjoys similar conditions, formed bands and patclies. 

 At Padstow the ground is too sheltered for the Callithamnion or 

 Nemalion belts, and time was not available for the exploration of 

 the exposed coast-line in that neighbourhood. Pools occur near 

 Padstow, as at Newquay and St. Ives, but Codium imicronatum 

 was completely absent. P. pluniosa also was not observed any- 

 where in Cornwall. 



4. North Wales. — As this area had not been visited, an effort 

 was made to obtain information by means of correspondence and 

 examination of herbarium collections. Professor E. W. Phillips, 

 of Bangor, was kind enough to supply notes, and also to lend a 

 number of specimens from the Anglesea neighbourhood (chiefly 

 Menai Straits and Puffin Island) from his private collection. The 

 examination of these showed that whilst P. pluviosa is plentiful in 

 North Wales, the other two plants, Callithamnion arbuscula and 

 Codium mucronatum, are not found. This was in agreement with 

 Professor Harvey Gibson's list of algae for the Liverpool Marine 

 Biological Committee's district (Trans. L.M.B.C. vol. v. 1891, a copy 

 of which was kindly lent me by the author)."^' Professor Harvey 

 Gibsoii writes that he has not found Codium mucronatum on the 

 north coast of Wales, but that Callithamnion arbuscula is plentiful 

 in the Isle of Man, and specimens from that locality exist in the 

 Kew collections. Mr. N. E. Brown, of Kew, has examined the 

 shore around Llandudno, and he tells me he has never observed 

 any species of Codium in the rock pools of that region. 



We are now in a position to summarize the facts as to the distri- 

 bution of these species. As far as Wales is concerned, P. plmnosa 

 is frequent on the rocky shores of north-west corner, but does 

 not appear to extend south of Anglesea ; Callithamnion arbuscula 

 and Codium mucronatum, on the other hand, though common in the 

 Isle of Man, do not reach the Welsh coasts at all. With regard 

 to the British Isles, the Callithamnion and Ptilota are general in 

 Scotland and descend as far as Yorkshire in the North Sea, and 

 are abundant in the warm waters of the west of Ireland, but in 

 the Irish Channel stop short at the Isle of Man and Anglesea 

 respectively. Both are supposed to occur in the south of Ireland, 

 but this requires confirmation. Codium mucronatum remains as 

 mysterious as ever. No trace of it has been seen in the localities 

 investigated in North or South Wales, and it may be safely stated 

 to be entirely absent from Devon and Cornwall. It is still only 

 known in Europe from the Atlantic shores of Scotland and Ireland 

 (where it has existed since the early part of last century) and from 



* A not irrelevant addition to that list may, however, be here noted, namely, 

 the ordinary Codium toinentosum, which was found by Professor Phillips and is 

 preserved in his herbarium. A fragment of a frond of Ptilota phuiiosa, in- 

 scribed " Ilfracombe E. T.," also occurs in his collection. But as the plant 

 does not occur in this well-worked region, the locality given must be regarded 

 as erroneous. 



