S5Q 



SYSTEMATIC HISTORY OF THE INFirSORlA. 



gonal areolation. This species is re- 

 markable chieiiy for the peculiar struc- 

 ture of its conuectiug zone, the plates 

 having- their communicating margins 

 serrated so as to fit into each other. 



T. grande (Br.). — Sides convex ; 

 angles attenuated, obtuse; hexagonal 

 cellules numerous. Diam. 1-100". Br 

 MJ. i. p. 249, pi. 4. f. 8. T. orientale, 

 Harv. & Bail. I. c. Indian Seas, Min- 

 danao. " The largest and stoutest spe- 

 cies of this genus " (Br.). The descrip- 

 tions do not suffice to distinguish this 

 species from large specimens of T. Favus. 



T. muricatum (Br.). — Sides straight ; 

 angles ending in a stout horn-like pro- 

 cess ; cellules large, hexagonal. Br M J. i. 

 p. 249, pi. 4. f 5. From the cleanings of 

 shells. A minute species, distinguished 

 by its pointed angles. Front view nearly 

 square, with the central portion smooth, 

 and the lateral ones turgid between the 

 prominent processes. 



T. ocellatum (E.). — Sides slightly con- 

 cave ; angles attenuated, obtuse ; cellules 

 unequal, large, hexagonal in the centre, 

 gTadually becoming smaller at the sides, 

 in no distinct order. KSA, p. 141. 

 Mouth of River Tenasserim, India. 



2t Lateral surfaces with three pseudo- 

 nuclei, not situated at the angles. 



T. sciilptmn (Sh.). — Sides straight ; 

 angles prolonged into conical points; 

 granules scattered ; surface with three 

 circular pseudo-nuclei, one opposite the 

 middle of each side. Sh MT. ii. pi. 1. 

 f 4. Natal, In form this species some- 

 what resembles T. aciitmn; but its pseudo- 

 nuclei are eminently characteristic. 



3t Frustides triradiate, with very 

 concave sides. 



T. Solenoceros (E.). — Triradiate, with 

 deeply concave sides; angles prolonged 

 into long, linear, obtuse arms; cellules 

 radiating. Br MJ. i. p. 248, pi. 4. f 1. 

 Bermuda earth, (vi. 15.) This species 

 differs from every other by its long linear 

 rays, which have neither pseudo-nodules 

 nor processes. 



T. Pileus (E.). — Somewhat triradiate, 

 with very concave sides ; angles tapering, 

 obtuse, with pseudo-nodules ; cellides 

 minute, radiating. EM. pi. 19. f. 18. = T. 

 brachiolatmn, Br MJ. i. pi. 4. f 2. Fossil, 

 Greece ; recent. New Zealand. Mr. 

 Erightwell refers his T. hrachiolatum to 

 the next species. 



T. PUeohis (E.). — Somewhat trira- 

 diate, with vcrv concave sides : angles 



produced, obtuse, with pseudo-nodules ; 

 cellides small, scattered. EM. pi. 35 a. 

 21. f. 17. = T. obtusum, Br MJ. iv. 

 p. 251, pi. 4. f. 20. Antarctic Ocean. 

 Resembles T. Pileus in form, but is 

 smaller, and its cellules are scattered. 



4t Frustules not triradiate ; angles with 

 pseudo-nodules, or minutely punc- 

 tated. 



T. concavum (Harv. & Bail.). — Sides 

 very concave ; angles rounded, minutely 

 punctated; cellules of centre arranged 

 in simple and forked radiating lines. 

 H. & B., Trans, of Acad, of Philadelphia, 

 1853. Tahiti. 



T. WaUiclui (Ralfs). ~ Valves with 

 minute radiate areolation, a row of mar- 

 ginal puncta, and a minute horn-like 

 process at each angle. = T. imnctutuin^ 

 Wallich, TMS. viii. p. 48, pi. 2. f. 21. 

 India, Atlantic. 



T. arcticum (Bri.). — Valves with 

 slightly convex or straight sides ; areo- 

 lations small, but distinct, radiating in 

 lines from the centre, and becoming mi- 

 nute at the angles, which are rounded 

 and slightly inflated. = T. Wilkesii, var. 

 /3, ■v\ath 4 angles ; Amphifetras Wilkesii^ 

 Bri MJ. i. p. 250, pi. 4. f 11; Ro TMS. 

 viii. p. 58. Beechey Island, Arctic 

 Regions; Puget's Sound, Vancouver's 

 Island ; and Montery stone. The speci- 

 mens obtained from Vancouver's Island 

 have proved that Triceratium has been 

 erroneously considered a free form, and 

 that its proper position is with Amphi- 

 tetras and Biddulphia; the specimens 

 alluded to show it attached to Zoo- 

 phytes, and the frustides connected at 

 the angles by a short stipes or cushion, 

 exactly like Amphitetras. 



T. Montereyii (Br.). — Sides concave ; 

 angles rounded, with pseudo-nodules; 

 cellides minute, largest in the centre, 

 which is much inflated. Br MJ. i. p. 251, 

 pi. 4. £ 8. Fossil. Monterey Bay. This 

 species is easily distinguished from T. 

 arcticum by its central boss and larger 

 cellules. 



T. punctatmn (Br.). — Sides straight ; 

 cellules large, puncta-like, scattered, 

 smaller at the rounded angles. Br MJ. 

 iv. p. 275, pi. 17. f. 18. Arctic Regions. 

 (VI. 20.) 



5t Angles without pseudo-nodules. 



T. formosum (Br.). — Sides slightly 

 concave ; angles obtuse, without pseudo- 

 nodules ; cellules very minute, somewhat 

 radiating. Br INI J. i. p. 250, pi. 4. f 10. 

 Shell cleanings from i/?)?^?o^)?<5 macuJatKS, 



