814 



SYSTEMATIC HISTORY OF THE INFUSORIA. 



■with five radiating lines, the other un- 

 known ; apex not truncate. KSA. p. 25. 

 Bemiuda. Diam. 1-480". Scarcely 

 more than a variety of the preceding 

 species. 



M. Rota (E.). — Valves large, one with 

 six, the other with seven radiating lines ; 

 apices entire. KSA. p. 25. Bermuda. 

 Diam. 1-360". Probably another variety 

 of 3/. Cnix. 



M. sexcmgida (E.). — Valves thin, one 

 with six radiating lines, the other un- 

 known; apex broadly tnmcate, with a 

 hexagonal ai'ea. EM, pi. 33. 17. f. 12. 

 Virginia. Diam. 1-1632". Resembles a 

 truncated six-sided cone. All the above 

 species are very smooth and crystal- 

 line. 



M. heptagona (E.). — One valve with 



seven, the other with nine rays; apex 

 truncated. Bai AJS. xlviii. pi. 4. f. 12. 

 Bermuda. Diam. 1-840". 



M. Ocxdus-Chamceleontis (E.). — One 

 valve having eight radiating lines and 

 tnmcate apex, the other unlmown. KSA. 

 p. 25. = Pyxidicula Oculus- Chamceleontis. 

 Maryland. Diam. 1-1152". 



M. Actinoptychtis (E.). — One valve with 

 9, the other with 13 flexuose radiating 

 lines ; apices broadly tnmcate. = Pyxi- 

 dicula ? Actinoptijchus, EM. pi. 18. f. 19. 

 Virginia. This species seems distinct in 

 its flexuose rays and the undulated mar- 

 gin of its umbilicus, (v. 59.) 



M. Discoplea (E.). — Valves small, 

 conic, with 18 to 20 rays ; apices smooth, 

 truncate. KSA. p. 25. In Patagonian 

 pumice. Diam. 1-1152". 



Genus STEPHANOGONIA (Ehr.).— Valves as in Mastogonia, but their 

 truncated apices have spinous angles. 



Distinguished by the rays being prolonged into spines, and forming a fringe 

 round the umbilicus. 



Stephanogonia quadrangula (E.). — 

 Valves thin, smooth, with truncated 

 apices, one having four, the other six 

 ray-like angles and spines. KSA. p. 26. 

 Bermuda, 



S. polygona (E.). — Valve with centi'al 

 portion smooth and much elevated, united 



to the margin by an indefinite number of 

 rays, the spaces between which are some- 

 times faintly pimctate ; the umbilicus 

 sometimes sm-rounded with spines. Vir- 

 ginia and Bermuda deposits. EM. pi, 33. 

 18, f. 10; Br JMS. viii. p, 97, pi. 5. 

 f. 8. (v. 57.) 



Genus CLADOGRAMMA (Ehr.).- 

 known to us. 



Cladogramma Californicum (E.). — 

 Valve orbicular, not cellulose, marked 

 ^vith flexuose lines radiating from the 



-The characters of this genus are un- 



centre, and irregularly forked or divided 

 near the margin. California. EM. pi. 

 33. 13, f. 1**. {y^u. 11,) 



Genus HYALODISCUS (Ehr.). — Erustules simple, disciform ; disc smooth, 

 flat, its umbilical portion or centre separated by a distinct sutiu'e. 



Kiitzing unites this genus with Cyclotella; but its comparatively large 

 hyahne disc, with a centre distinguished by an evident suture, and usually 

 somewhat coloured, is perhaps sufiicient to justify its removal. Its flat disc 

 will distinguish it from Podosira. 



YiYA.'LOJ)iBCV^Patagonicus(E.'). — Disc 



large, very smooth, its margin separated 

 from the large centre by a slightly 

 grooved but not denticulate suture ; 

 imiction-line in front view very tumid. 

 EM. pi. 38, 22. f. 10, 11. In pumice 

 from Patagonia. Diam. 1-432". 



II. IcBvis (E.). — Disc large, smooth, its 

 central portion separated by a fi'acture- 

 like suture. EM. pi. 33. 15. f. 17. Cyclo- 

 tella /^r?'s,Kiitz. Virginia, Diam. 1-456". 

 Allied to Cyclotella physoplea. The su- 

 ture between the valves is not tumid. 



and the central portion of the disc is 

 smaller, and hence more distant from 

 the rim, than in H. Patagonicus. 



H. steUiger (Bai.). — Disc with a broad 

 margin covered with distinct rectilinear 

 rows of dots, arranged in groups so as 

 to produce a stellate appearance. BC. 

 vii. Abundant. St. Augustine, Florida. 

 " The markings in this species are quite 

 distinct; and the stellate appearance, 

 resembling that shown by Coscmodiscus 

 stibtilis, will at once distinguish it from 

 all other species," B. 



