Diatoma.} ALGJE DIATOMACEJE. 405 



ous species, scattered sparingly among other individuals of the genus. 

 The auricular angles give to the frustula the appearance of microscopic 

 wool-packs. 



2. D.obliqudtum, Lyngb. {oblique-jointed Diatoma); filaments 

 short unequal, the joints oblique half as long again as they are 

 broad punctate and transversely banded — Lyngb. Hydroph. 

 Dan. 181. t. 62? Ag. Syst. Alg. p. 6. — Conferva obliquata, 

 E. Bot. t. 18G9. 



Parasitic on various small marine Algcc. — I believe the only British 

 specimens are those which were discovered by Miss Biddulph, growing on 

 Cladosiephus verticillatus and Gigartina suhfusca. — The whole tuft is not 

 more than one or two lines in length, but distinguishable by the unassisted 

 eye. The cohesion of the frustula is not confined to the alternate 

 angles. Lyngbye's figure does not quite agree with that in E. Bot., and 

 may prove a distinct species. 



** Frustula (or joints) square, (not rounded) 



3. D. anipunctdtum, Ag. (one-spotted Diatoma); filaments 

 transversely striated, the joints equal in length and breadth 

 bearing- a central rose-coloured spot. — Ag. Syst. Alg. p. 6. — 

 Fragihiria unipiutctata, Lyngb. Hydropic. Dan. p. 183. t. 62. — 

 Achnanthcs nn /punctata, Grev. Crypt. Fl. t. 287. 



Parasitic on various Pulysiphonice, Kctorarpi, &c. Appin, Captain 

 Carmichael — Filaments very minute, giving the plants on which they 

 grow a pubescent character. The lowest joint is furnished with a stipes, 

 in the manner of an Achnanthcs : but there is cohesion at the alternate 

 angles of the frustula. 



4. D. Biddulphidnum, Ag. (Miss Biddufph's Dialoma); fila- 

 ments unequal, the joints longitudinally Striated and traversed 

 with a white band bearing a central red punctated mass. — Ag. 

 Si/sf. Alg. p. 5 Conferva Biddtttphiana\ 27. Bot* t. 1762, 



Parasitic on various filiform marine Alga. Southampton Mm Bid- 

 dulph. November and December. — I do not possess a Bpeobueuof this 

 remarkable plant. ThejVamenU are said to be half an inch long, and 

 the joints arc represented as variable in their length and breadth ; the 



general proportion is probably nearly equal. 



5. I). siiKiiitliim. Ag. (banded Diatoma); filaments: Boniewhal 



Curved pellucid at flic articulations, the joints nearl\ Bfl long RJ 

 they are broad, densely and t rUMl ei --ely striated — An. Syst. 



t \hi. />. i). — I). arcuatttm t Lyngh. Hydroph* Dun. p. 1m>. /. (>:- > . — 

 Conferva snrtotefa, fi. Bot t. 191 



Parasitic on various filiform marine A/gee, Discovered at Cromer 

 1»\ Dr. Hooker. Brighton, Mr. i; rrer, Plymouth, > 



Appin, Capt. Carmichael IYitli of Forth, JDr. Grevilie. Spring. — The 

 curved, broad, densely striated JUamenUt distinguish this from evert 

 other species. The colour under the microscope, is a | h -yel- 



low. '1 he filaments are half an inch or piorp in length ; but from the 

 deciduous nature, of the joints, are often found much shorter* 



c>. I>. marii uw, Lyngb. (J / i . t li 



