i899-] FosiyiE. — A Visit to Rotmdstone in April. 179 



scattered specimens of Squa?nariace<z and crustlike Litho- 

 thamnia, together with a perforating alga, Conchocclis rosea. 

 Probably another species nearly related to the latter was 

 observed infesting the central parts of a Lithothamnion at 

 station 1. Of animals in the above hauls, there was observed 

 a fine specimen of a Dentalhim, the shell of which was made 

 up of fine sand-grains firmly cemented together. 



After the work of dredging, we divided our attention 

 between encrusting Lithotham?iia and the other seaweeds to 

 be found between tides. South and south-west of Roundstone 

 Bay, in somewhat exposed rock-pools, we found L. i?icrustans 

 (L. polymorphum, Harv.) to be very abundant. This seems to 

 be a species capable of rapid growth, and is of interest as 

 showing the great variation brought about in the struggle for 

 existence between seaweeds and animals. In the most 

 exposed places at " The Beaches,"" we met with well-developed 

 specimens in fruit of Phymatolithon polyinojplmm, a rather 

 northern calcareous alga. Closely associated we found an 

 interesting form of L. lichenoides nearly related to that form 

 figured by Harvey in Phycologia Britannica, showing that also 

 this species varies according to the nature of the locality. 

 We also met with several Melobesice, and L. Cro7iani> not 

 formerly found in Ireland. This species was found here, as at 

 other places, growing on the stems of Laminaria hyperborea, 

 together with Melobesia laminarics, but more scarce than 

 farther north. Of other algae we met with numerous speci- 

 mens of Ch<ztoviorpha acrea mixed with Cladopho?a hirta 

 and Ch<ztomorpha tortuosa. In deep rock-pools at about 

 half- tide we observed luxuriant plants of Desmatestia ligulata 

 and Ralfsia sp., as well as other interesting species, among 

 these many parasites and epiphytes partly infesting Cysloseira, 

 partly other algae, but not yet worked at, as they require 

 microscopic examination. One of us also met with in these 

 rock-pools a few specimens of the starfish known as Asterina 

 gibbosa, while on the other hand the well-known boring sea- 

 urchin, Strongylocentrotus lividus, which is common along the 

 west coast, was observed in abundance. Many of the urchins 

 were nearly concealed under a crust of L. i?icrusta?is. 



The calcareous algae did not appear to be made use of here, 

 as in other parts of Ireland, for manuring purposes. But on 

 the shore, close to "The Beaches," there were many heaps of 



