Clare Island Survey — Marine Algae. 15 113 



Vaucheria coronata Nordst. 

 Easily recognized when in fruit by the fecundation-tubes which crown 

 the oogonia. It occurs on the upper parts of muddy shores in which it forms 

 beautiful velvet-like sheets of a deep green colour. It is common at Louis- 

 burgh (Bimowen River), Annagh Island, and Mulranny, and was found in 

 spring, summer, and autumn. 



V. litorea Agardh. 

 Common on the muddy shores of the inner part of Clew Bay. It is 

 monoecious, and fruits freely, Belclare material showing abundance of ripe 

 oogonia in May, 1911. The latter are subglobose, and borne on the extremity 

 of straight or recurved branches which in many cases appear to represent the 

 main shoot, indicating that the branching is of a sympodial nature. 



Codium amphibium Moore. 



This rare species was found on a ledge at the mouth of a cave on Clare 

 Island (1909 and 1911). In 1909 its identity was doubted, as it appeared 

 possible that the specimens represented a crop of young plants of 0. tomeniosum. 

 But in August, 1911, a much more characteristic growth was found in the 

 same cave, the sheet measuring some 15x9 inches. A passing shower proved 

 fortunate in showing that the patch occurred in a spot where rain dripped 

 from the roof, which confirmed its claim to be amphibious. 



A special search for the plant was made at Boundstone (from whence 

 it was described in 1843) during September, 1911, but without success. The 

 amount of suitable ground in the neighbourhood is large, and though not 

 discovered in a one-hour search, it is quite possible that it still exists. 



In the Clare Island specimens, the fronds are 5-8 mm. high, and 1*5-2 mm, 

 thick ; the full-grown utricles are clavate and thin at the apex ; they measure, 

 on the average, 500 x 150 ji. The creeping filaments forming the effused 

 stratum at the base are freely branched, somewhat irregular, and contain much 

 chlorophyll ; they vary from 30-50 ju in thickness. Though a large number of 

 fronds were examined, no fertile utricles were found. Outside Ireland. 

 C. amphibium lias been recorded from Cornwall and the Isle of Man. 



C. tomentosum Stackh. 



As great difficulties exist in many countries with regard to the limitations 

 of C. tomentosum, a full description is here inserted. The species varies 

 considerably, and has been recorded from all parts of the world ; but as it was 

 originally described from an English specimen, the British plants may be 

 regarded as typical. 



R.I.A. PROC, VOL. XXXI. P 15 



