836 



SYSTEMATIC HISTORY OF THE INFUSORIA. 



Genus ASTEROLAMPRA (Ehr.).— Frustules simple, disciform ; disc orbi- 

 cular, with marginal areolated or punctated compartments, separated by 

 smooth rays which proceed from a hyaline central area ; central area divided 

 by lines, which radiate from the umbilicus to the apex of each compartment ; 

 compartments and rays symmetrical. Marine. The disc in this beautiful 

 genus is generally colourless, and when mounted in balsam is far from con- 

 spicuous, notwithstanding its comparatively large size. The marginal com- 

 partments are usually conical, and from the apex of each a line or rib proceeds 

 to the umbilicus. The hyaline central area seems to originate from the dilated 

 inner ends of the rays, and its lines to be produced by their jimction. Aste- 

 rolampra is distinguished from Asteromphalus by the compartments being 

 similar and equidistant ; on which account the rays are equal, the lines all 

 radiant, and the umbilicus central. 



* Umbilical lines straight. 



AsTEROLAMPEA Manjhmdica (E.). — 

 Umbilical lines simple, straight; areo- 

 lated compartments conical or semicir- 

 cular. EB. 1844, p. 76, f. 10 ; Wallich, 

 TM. viii. p. 47, pi. 2. f. 13, 14; GrevTM. 

 viii. p. 108, pi. 3. f 1-4:.= A. septenaria, 

 Johns. Sill. Journ. 2ud ser. xiii. p. 33 ; 

 A. impar, Sh TM. ii. pi. 1. f 14 ; A. pe- 

 lagica, EB. 1854, p. 238. Fossil, Vir- 

 ginia : Monterey stone, guano. Recent, 

 India, &c. (xi. 33.) Rays 6 to 14. The 

 disc varies greatly, not only in the num- 

 ber of rays, but in the elongated or de- 

 pressed form of the compartments, pro- 

 ducing a corresponding variation in the 

 size of the central area. 



A. Rotala (Grev.). — Resembles A. 

 Marylandica, but the areolated compart- 

 ments have subtruncate apices ; umbili- 

 cal lines straight. GrevTM. viii. p. Ill, 

 pi. 3. i. 5. Monterey stone. Umbilical 

 lines simple or dividing in a forked man- 

 ner, close to the central point. 



A. variahilis (Grev.). — Compartments 



with cuneate apices ; umbilical lines 

 straight, mostly united in twos or threes 

 near the central point. Grev TM. viii. 

 p. Ill, pi. 3. f. ^^. Monterey stone. 

 Rays 6 to 11. 



A. Grevillii (Wallich, Grev.). — Com- 

 partments conical, with truncated apices ; 

 umbilical lines straight, variously united. 

 ^= Asteromphalus Grevillii,^ si]\ TM. viii. 

 p. 47, pi. 2. f. 15 5 Asterolampra Grevillii, 

 GrevTM. viii. p. 113, pi. 4. £ 21. Fossil, 

 Viro-inia and Monterey stone ; recent, 

 Indian Ocean. This species approaches 

 Asteromphalus in the appearance of the 

 central area, but its marginal compart- 

 ments and alternating rays are symme- 

 trical. Rays numerous, 13 to 17. 



2 * Umbilical lines angularly bent. 



A. Brebissoniana (Grev.). — Areolated 

 compartments trmicated ; umbilical lines 

 with an angular bend in the middle. 

 Grev TM. viii. p. 114, pi. 3. f 9. Mon- 

 terey stone. Umbilical lines simple or 

 united, close to the central point. 



Genus ASTEROMPHALUS (Ehr.).— Frustules simple, disciform ; chsc as in 

 Asterolampra, but \^-ith two of the punctated compartments approximate, and 

 the interposed ray narrower than the others. Marine. Asteromphalus differs 

 from Asterolampra in having two compartments closer together. The lines 

 connecting these with the umbilicus do not radiate like the rest ; and the 

 enclosed hyaline ray consequently differs in form from the others, and is 

 termed the median or basal ray. 



* Umhilical lines radiating frorn a central 

 point, two of them approximated. As- 

 teromphalus. 



t Umbilical lines straight or curved. 



Asteromphalus Hooherii (E.). — 

 Punctated compartments, conical or 

 rounded at the apex ; umbilical lines 

 straight, the median ones parallel. EB. 

 1844, p. 200; EM. pi. 35 a. 21. f. 2. =A. 



Buchii, EB. 1844, p. 200; A. Humboldtii, 

 E. /. c. p. 200 ; EM. pi. 35 a. 21. f 3 ; J. 

 Cuvierii, EB. 1844, p. 200 ; EM. pi. 35 a. 

 21. f 1. Antarctic Ocean. (xf34.) Rays 

 6 to 9. A\'e consider that forms differing 

 only in the nmnber of their rays are not 

 really distinct, and have consequently 

 united Ehrenberg's species quoted above. 

 A, Dallasianus (Grev.). — Areolated 

 compartments, with truncate apices ; me- 

 dian lines campanulate. = Asterolampra 



