838 



SYSTEMATIC HISTORY OF THE INFUSORIA. 



lical lines radiate from the upper half 

 of the median ones, and are sometimes 

 divided. The angular bend is nearer the 

 outer end than in any other species ; and 

 at each angle is a minute spine-like pro- 

 cess, Grev. 



A. Roper ianus (Grev.). — Disc circular, 

 with its hyaline area centrical ; areolated 

 compartments, truncate, almost equal ; 

 umbilical lines radiant from rovmded 

 end of median ones ; median lines pass- 

 ing round the central point in a semi- 

 circle, then contracted, and lastly widely 

 expanded. = Asterolamjva Roperiana, 

 Grev M J. \i\\. p. 120, pi. 4. f. 14. Indian 

 Ocean. Rays 7, robust ; areolation rather 

 large, Grev. 



A. ShadhoUianus (Grev.). — Areolated 

 compartments, truncate ; umbilical lines 

 radiant from the pyriform median ones, 

 with the bend about the middle ; rays 

 not reaching the \\\?iT:^m.=Asterolampra 

 Shadboltiana, Grev MJ. viii. p. 121, pi. 4. 

 f. 19. Indian Ocean. '' Rays 7, robust ; 

 areolation rather large. Its nearest ally 

 is perhaps A. Brookei, from which it is 

 separated by the very diflerent median 

 lines and by the angular bend being 

 more in their middle" (Grev.). Dr. 

 Greville suspects that in this species, as 

 in A. Roperiaims, A. heptactis, and A. 

 Arachie, the number of rays may be 

 more constant than is generally the case 

 in the group. 



A. heptactis (Breb.). — Areolated com- 

 partments, truncate ) rays broad, linear, 

 terminating in a lunate marginal fold, 

 and bordered by a row of larger areolae. 

 = Spatangidium heptactis, Breb. Bull. Soc. 

 Linn, de Normand. iii. p. 3. f. 2 ; Aste- 

 rolampra heptactis, Grev TM. viii. p. 122 ; 

 Spatangidium Ralfsianum, TM. vii. p. 161, 

 pi. 7. f. 7, 8. Peru\dan and Californian 

 guanos, Atlantic soundings. Rays 7, 

 straight or slightly curved, the median 

 one in a broad shallow groove, the linear 

 portion faintly prolonged through the 

 dilated portion to spurs fi'om the bends 

 of the adjacent umbilical lines. Areo- 

 lation of compartments, conspicuous; 

 disc subcircular. (-^tii. 21.) 



Doubtful or imperfectly described 

 Species. 

 A. centr aster (Johnston). — Disc orbi- 

 cular ; areolated compartments with 



i roimded apices and bordered by a series 

 j of larger areolae ; umbilical lines straight, 

 I radiating from top and sides of median 

 I ones ; rays terminating at the margin in 

 j nodules. Johnston, MJ. viii. p. 12, pi. 1. 

 f. 10. Elide guano, (viii. 14.) Rays 

 11. Dr. Johnston's figure diflers from 

 eveiy known species by having the rays 

 continued, as Dr. Greville remarks, like 

 distinct bars or the ribs of an umbrella, 

 from the central point to the margin. 

 We believe, however, that this structure 

 is similar to what is met with in several 

 other species of Asterolampra and As- 

 teromphalus (see especially Gre-vdlle's 

 figures of Asterolampra variabilis, A. 

 Wcdlichiami, A. Roperiana, and A. hep- 

 tactis), but more strongly marked, and 

 probably exaggerated in the figure. 



A. stellatus (Grev.). = Asterolampra 

 stellata, Grev TM. viii. p. 124, pi. 4. f. 20. 

 Indian Ocean. It is allied to A. Hilto- 

 nianus and A. JlaheUatus. The lowest 

 pair of umbilical lines are cm*ved down- 

 wards, as in the former species. The 

 median lines are parallel. The valve, 

 at a first glance, is most conspicuous for 

 the large size of the hyaline area and the 

 rapidly attenuated rays; but this may 

 prove to be a worthless distinction. 



A. Sarcophagus (Wall.). — Valve ob- 

 long, with inflated middle ; median ray 

 plane and continuous with the anterior 

 rav ; umbilical lines straight ; areolation 

 very large. Wallich, TM. viii. p. 47, pi. 2. 

 f. V2.=i Asterolampra Sarcophagus, Grev 

 TM. viii. p. 124. Indian Ocean. " The 

 broadest portion of this species is always 

 towards the extremity opposite to the 

 median ray, thus gi\-ing the valve a some- 

 what p^a'iform or sarcophagus-like shape" 

 (Wallich). " The form of ihQ valve is 

 so extreme a deviation from the other- 

 wise more or less orbicular shape of the 

 entire series, that an impression almost 

 forces itself upon the mind tJiat it is 

 simply a malformation. It is most nearly 

 related to A. Ai-achne ; for if we remove 

 the terminal ray (which in many species 

 may be either absent or present), the five 

 remaining rays would occupy the relative 

 position M^hich they hold in that species, 

 as well as in the same direction, one pair 

 pointing upwards, the other pair down- 

 wards. In both species the areolation is 

 large" (Grev.). 



Genus ASTERODISCIJS (Johnson). — Frustules simple, disciform; disc 

 divided into punctated compartments, which do not reach the centre, by hyaline 

 smooth rays ; compartments connected to the umbilicus by an equal number 

 of radiating lines, two united half way, the rest distinct. Fossil. (Johnson, 



