NEW OR CRITICAL BRITISH MARINE ALG^. 385 



G-5 /x in diameter. Articulations nearly square or slightly longer 

 than broad ; colour a dark purple-red. On an old shell dredged 

 at the mouth of the Yealm, G-. Brehner. 



This variety differs from the typical form in the slightly greater 

 thickness of the trichomes, which are of a deep, clear, purplish red 

 colour, instead of the light bluish green of ordinary specimens ; the 

 patches are also much smaller, and the filaments are not collected 

 into such evident teeth. 



3. MicROcoLEUS TENERRiMUS Gom. Monog. Oscil. 93. On rocks 

 near high-water mark, Torquay, E.A.B. Easily distinguished 

 from the only other marine species of Microcoleus found on the 

 shores of Britain by the slenderness of the trichomes, which are 

 only 1 to 1-5 /x in diameter and sharply pointed, and by the smaller 

 number of them contained in each sheath. 



4. Hyella ciESPiTosA Bomct et Flahault in Morot Journ. de 

 Botanique, ii. 162 ; var. nitida, nov. var. Filaments clear purplish 

 carmine, much and irregularly branched, and more slender than in 

 the typical form ; cells varying from square to several times longer 

 than broad, frequently divided longitudinally (chroococcoid fila- 

 ments, however, are rare) ; five, six, or more contiguous cells of 

 the same filament often simultaneously converted into short, 

 simple, forked, or irregularly-branched chains of sporangia. In 

 old shells from deep water, Weymouth, E.A.B.; Malahide, T. 

 Johnson; Plymouth, G. Brcbner. 



The colour of this alga is clear purplish-pink, not unlike that 

 of Conchocelis rosea, with which it is frequently associated, but very 

 unlike that of typical Hyella ca^spitosa, from which it is also dis- 

 tinguished by many slight differences more easily seen than described. 

 It is by no means improbable that it is really specifically distinct 

 from Hyella ccespitosa, but I have seen too few specimens at present 

 to be certain that the characters are constant. 



It is worthy of remark that OsciUatoria rosea, the variety of 

 Symploca atlantica described above, and the present variety, all of 

 them obtained from deep water, where one would not expect to find 

 any Myxophycea, are of the same purplish-red or pink colour, while 

 specimens of the same genera obtained from the shallow water near 

 high-water mark are always bluish green or greyish purple. 



5. Ralfsia disciformis Crn. Fiorule du Finist. 166. Dredged 

 from deep water near the mouth of the Yealm, and in Plymouth 

 Sound, G. Brehner. 



Plymouth specimens agree well with those distributed in Des- 

 mazieres' exsiccata by the brothers Crouan. As a species, however, 

 it must be confessed that the plant comes too near to //. clavata, 

 from which it is distinguished by the shorter, less clavate para- 

 physes, which are often composed of but one or two cells, and are 

 then hardly any longer than the sporangia. 



6. LiTHODERMA siMULANS ( = Sovupion swiidaus Kuckuck, Bemerk. 

 zur Mar. Aly. Hehjoland, 236). " Queen's Ground," Plymouth. 

 I detected this species on some old shells dredged from the Queen's 

 Ground, Plymouth, and sent to me by Mr. Brebner. The species 



