OF THE EUrODISCEiE. 



843 



podisciis, Pentapodisciis (E.), Podisciis (Bail.). The cellular structure is 

 usually less evident in this genus than in Coscinodiscus. 'W^'e have removed 

 to Actinocyclus thi^e species originally placed here by Professor Smith, who 

 himself admits that they probably belong to that genus, " as the process in all 

 is rather a pseudo -nodule than a projection from the surface of the valve." 



EuPODiscus Argus (E.). — Disc with 

 three or more processes, subremote from 

 the margin ; cellules somewhat stellate, 

 intervals punctated. SD. i. p. 24, pi. 4. 

 i. 39. = E. Amencam(s, EB. 1844 ; K 

 quaternarius, E. quinarius, E. Germa- 

 nicus, KA. p. 134. (xi. 2: xi. 41, 42.) 

 Recent in marine and brackish water, 

 Europe, America ; fossil. United States. 

 This species is easily recognized by its 

 irregular cellules and intervening puncta, 

 which give to the disc a clouded appear- 

 ance, very unlike the usual transparency 

 of Diatomaceae. The processes vary from 

 3 to 5 in number. " The star-shaped 

 cells appear -when seen by direct light 

 to be placed in the centre of small bosses 

 or protuberances, in which respect it dif- 

 fers from all other Diatomacese that I 

 am acquainted with. Ro MJ. ii. p. 73. 



E. motistnwsiis (E.). — Disc with 4 pro- 

 cesses on one side. E. /. c. p. 81. Baltic. 

 Distinguished by the unsymmetrical dis- 

 position of its processes. It is probably 

 an accidental variety of E. Argus. 



E. Roger sii (Bail., E.). — "Frustules 

 large, having 3 to 7 hyaline lateral pro- 

 cesses placed on an elevated circle, 

 within which the disc is slightly con- 

 cave, and outside of which the surface 

 is part of the frustum of a cone. = Po- 

 discus Rogersii, BAJ. xlvi. pi. 3. f. 1, 2 ; 

 Eujjodiscus Rogersii, E. /. c. ; E. Bailegii, 

 E. /. c. Recent and fossil. United 

 States. In this species the processes 

 are close to the rim. The whole surface 

 is beautifully punctate. ... As this spe- 

 cies is the largest and most beautiful of 

 the fossil Infusoria occurring in the strata 

 of which Professor W. B. Rogers made 

 the discovery, I have selected it as pe- 

 culiarly appropriate to bear his name " 

 (Bail. /. c). 



E. radiatus (Bail.). — Disc plane, areo- 

 lation hexagonal, with 4 (or more) sub- 

 marginal processes. " Resembles Cosci- 

 nodiscus radiatus in size and reticulation," 

 BC. Bri MJ. viii. p. 95, pi. 5. f. 10. 

 America. 



Genus AULACODISCUS (Ehi\). — Frustules disciform ; disc granulated, and 

 furnished with intramarginal, shortly tubular processes, each connected with 

 the centre by a distinct furrow, or by a radiant series of more conspicuous 

 granules. Aulacodisci are Eupodisci furnished vdih. bands radiating from the 

 centre and connected with the tubercles situated just within the margin, and 

 having the surface of their valves granulate, and not cellular. Professor 

 Kiitzing makes this genus a section of Eupodiscus. 



rows aud about the umbilicus; margin 

 finely striated. In order to observe the 

 disc properly, it is necessary, on account 

 of its imevenness, to vary the focus. 

 Specimens from New Zealand have the 

 granules and markings more distinct, 

 and the inflations smaller, less definite, 

 and further from the margin. 



A. formosus (Aiiiott, MS. ) . — Disc kuid, 

 ha\ing an irregular perforation-like um- 

 bilicus, a large cuneate inflation beneath 

 each process, and radiating series of con- 

 spicuous pearly granules. = A. Bright- 

 ivellii, Ralfs, MS. ; A. Boliviensis, Breb. 

 MS. In upper Peruvian or San Filipe 

 guano. A. formosus agrees with A. 

 Petersii in having an inflation beneath 

 each process, but differs in most other 

 respects. From A. margaritaceus and 

 A. Comheri, which it more nearly re- 

 sembles in the appearance and arrange- 



* Disc huUate heneath the processes. 



AuLACODiscus Petersii (E.). — Disc 

 nearly colomiess, having a small, per- 

 foration-like umbilicus, a large kite- 

 shaped inflation, rough with minute 

 points, beneath each process, and minute 

 granules an-anged in lines. EB. 1845, 

 p. 361. = Eupodiscus Petersii, KS A. p. 135 ; 

 E. cruciger, Sh TM. ii. pi. 1. f. 12. South 

 Africa, both recent and in guano ; Aus- 

 tralia and New Zealand. Disc large, 

 ■w-ith 3 to 5 orbicular processes, fm-nished 

 with a central nipple and situated on 

 the outer margin of the inflations. The 

 granules are minute, and arranged in 

 lines, some radiant and bisecting the 

 intei-vals between the processes, the rest 

 oblique and decussating. Raised points 

 are present on the inflations and less 

 conspicuously along the connecting fur- 



