MARINE ALGAE. 



PROBABLY no portion of the littoral of these Islands has been more thoroughly 

 explored by competent algologists than the shores of the Firth of Clyde ; 

 yet, owing to the great extent of coast, which, following the indentations, 

 extends for several hundred miles, much remains to be done. The more 

 outlying portions of the great Lochs, the Western shores of Bute and Arran, 

 and the Peninsula of Kintyre, are almost a terra incognita to the phycolo- 

 gist ; while hardly more than a beginning has been made with the exploration 

 of the great Zostera beds at Fairlie, and the extensive banks of Lithothamnia, 

 which are so plentiful in the districts around the Cumbraes and Arran. 



The marine flora of the Firth of Clyde is Northern in its general character- 

 istics, as is clearly indicated by the great number of Fucoidea which it 

 contains ; yet side by side with such typically Northern species as Mono- 

 stroma Blyttii, Gobia baltica, Dictyosiplion hippuroides, D. Chordaria, D. 

 Mesogloea, Stictyosiphon tortilis, Phaeosaccion Collinsii, Odonthalia dentata, 

 Antithamnion floccosum, etc., we meet with Bifurcaria tuberculata, Cystoseira 

 ericoides, C. granulata, Dasya arbuscula, Nemalion lubricum, Delesseria 

 hypoglossum, Sphaerococcus coronopifolius, Naccaria Wigghii, Scinaia furcel- 

 lata, Callyonema reniformis, Chondria tenuissima, Champia parvula, Mono- 

 spora pedicellata, Halarachnion ligulatum, and others equally typical of a 

 Southern flora. 



With the exception of the Orkney Islands nowhere else on the British 

 coasts can a similar mixture of Northern and Southern forms to the same 

 extent be met with. As is well known, the temperature of the water is the 

 most important factor regulating the distribution of marine algae, and 

 "Gulf-stream influence" is usually considered responsible for this great 

 influx of Southern forms into the algae-flora, of both the Clyde Sea- Area 

 and the Orkney Isles. 



The algae of the district have always presented peculiar attractions to 

 botanists since the days of Lightfoot and Greville, Arnott and Hennedy, to 

 those of Robertson and the workers of the present day, most of whom have 

 at one time or other algologised in the district ; but it is to the labours of the 

 indefatigable Mrs. Robertson who, for many successive years, and at all 

 seasons, continued her search for the sea-weeds of the neighbourhood, that 

 we owe most of our knowledge of the marine algae of the Firth of Clyde. 



Phaeosaccion Collinsii and Lithothamnion Batter sii are to be met with 

 nowhere else in Europe, and Ectocarpus ovatus, Halicystis ovalis, Leptonema 

 fasciculatum, and Lithothamnion orbiculatum, are hardly known to occur in 

 Britain outside the Firth of Clyde, while Urospora collabens had not been 

 found on our coasts since 1808 when, in March, 1894, it was rediscovered by 

 the late Dr. Robertson growing on a wooden buoy in the harbour of 

 (Jumbrae. 



