'70 



SYSTEMATIC HISTOKT OF THE LNFUSOillA. 



and lose themselves towards the pointed extremity which forms the base ; 

 such is the structure of Podosphenia and Ehipidophora. Viewed on one 

 side, that is, on the lateral surfaces, they present an obovate arch, marked 

 on the periphery of the surfaces themselves. The margin of this arch is 

 tliickened by the presence of the canal, which, seen in front, presents in the 

 cm*ve its brightness with an appearance of perforation." (Meneg I.e. p. 463.) 

 Professor Smith says that " a close examination of the frustules shows us 

 that the distinct and even moniliform striae so conspicuous in Podosphenia 

 are almost wholly wanting in our native species of Ehipidophora." The 

 stria3 in the former genus, however, are not always detected with facility, 

 since Meneghini remarks that " of the nine species described and figured by 

 Kiitzing, only one (P. Ehrenhergii) presents transverse striae on the secondary 

 sm^faces." Careful observation of the species of Ehipidophora in a gromng 

 state will probably prove that several of them have been constituted upon 

 insufficient grounds. It is to be feared, indeed, that characters taken from 

 the comparative length and stoutness of the stipes, its simple and branched 

 condition, and even the shorter or longer form of the wedge-shaped frustules 

 in the front view, are more or less fallacious. We believe that at least some 

 of the species are at first furnished with a short, thick, simple stipes, beaiing 

 the associated frustules at its apex, and that by the process of growth the 

 frustules become longer in proportion to their breadth, and lose theii^ flabel- 

 late arrangement by the subsequent elongation and dichotomous division of 

 the stipes. 



Ehipidophora cj^ystalUna (K.). — 

 Shortly stalked, flabellate ; frustules 

 shortly cuneate, rather broad, obtuse at 

 the base. KB. t. 9. I 10. 5. German 

 Sea. 1-1200" to 1-1300" 



E. (Edipusilv.). — Very shortly stalked, 

 siibflabellate ; frustules oblong cuneate, 

 truncate at the base ; stipes hemisphe- 

 rical. KB. t. 18. i. 5. 5, 7. Europe. 

 1-600" to 1-480". 



E. Anglica (K.). — Shortly stalked, 

 flabellate ; frustules turgid, cuneate with 

 truncate base and obtuse terminal angles; 

 stipes rather long, simple, thick. KB. 

 t. 27. f. 5. 2,4. Europe. 1-600". 



E. Ansfralis (K). — Flabellate; frus- 

 tules narrowly cuneate with truncate 

 base ; stipes simple, thick. KB. t. 9. 

 f. 5. Trieste. 1-540". 



E. horealis (K.). — Flabellate ; frus- 

 tules large, oblong cuneate with slightly 

 obtuse base ; stipes simple, rather stout. 

 KB. t. 9. f 6. Heligoland. 1-310". 



E. Nubecula (K). — Frustules hyaline, 

 broadly cuneate, somewhat acute at the 

 base, scattered, subsolitary or fasciculate, 

 lateral and terminal ; stipes filiform, 

 elongated, subramose. KB. t. 8. f 16. 

 Europe, (xiii. 17.) 1-720" to 1-600". 



E. teneJla (K.). — Minute ; fi-ustules 

 small, broadly cuneate, conjoined in an 

 imperfectly flabellate manner, acute at 

 the base ; stipes slender, very finely 

 branched. KB. t. 11. f. 3. Europe. 

 (XIII. 15.) 1-1080" to 1-960". 



E. Dalmatica (K.). — Flabellate in a 

 radiatiug manner; frustules oblong cu- 

 neate ; stipes short, rather stout, at leiigth 

 subramose, tubular. KB. t. 9. f. 7. 

 Europe. 1-540". Lateral view narrow- 

 clavate with very obscure strise. 



E. ahhreviata (Ag., K.). — Subflabel- 

 late ; frustules broadly cuneate with acute 

 base ; stipes rather thick, at length 

 branched. KB. t. 9. f. 14 = Licmophora 

 ahhreviata, Ag. Europe. 1-540". " Ee- 

 sembles R. paradoxa, but is distinguished 

 by its green colour when dried." (Ag.) 



E. paradoxa (Lyngb., K.). — Frustules 

 short ; broadly cuneate, somewhat acute 

 at the base ; stipes slender, filiform, di- 

 chotomous ; lateral \aew clavate. SBD. 

 i. p. 84, pi. 25. f. 231 = Gomplionema 

 paradoxnm, Ag. 1-540" to 1-480". Co- 

 lom'ing matter dull olive. The frustide, 

 especially in dried specimens, often has 

 its angles so much rounded as to become 

 obovate, — a character, however, not 

 peculiar to this species, (iv. 8.) 



E. tincta (Ag.). — Frustules elongated, 

 narrow cuneate, mth somewhat acute 

 base ; stipes elongated, subdichotomous, 

 slender. = Gom. tinctum, A Consp D. 

 p. 35 ; R. ehmgata, KB. t. 10. I 6. 

 1-310". Colom-ing matter dull olive. 

 According to Agardh, it differs from R. 

 jmradoxa in its greener colour and longer 

 and more slender frustules. He also 

 states that it resembles smaller states 

 of LicmopJwra Jiahellata, but is shorter 



