OF THE ANGFLIFEREJE. 



857 



Mr. Brightwell finds this species varj^ng, 

 with four and five angles. The front 

 view is quadrate, not constricted, the 

 angles produced into conical processes, 

 between which the margin is nearly 

 straight. 



T. condecorum (E.). — Sides straight 

 or slightly convex, with obtuse angles ; 

 cellules ver}' minute, diverging in curved 

 series. Br MJ. i. p. 250, pi. 4. f. 12. 

 Fossil. Bermuda. 



T. ohtusum (E.). — Sides very convex; 

 angles rounded, without pseudo-nodules ; 

 cellules circular, scattered. EM. pi. 18. 

 f. 48, 49. Virginia. 



T. Amhlyoceros (E.). — Sides concave ; 

 angles broadly rounded, without pseudo- 

 nodules ; cellules minute, somewhat 

 radiating. EM. pi. 18. f. 51. Virginia. 

 This species has more rounded angles 

 and smaller cellules than T. obtusum. 



T. Reticulum (E.). — Sides straight ; 

 angles subacute, vvdthout pseudo -nodules ; 

 cellules minute, numerous. EM. pi. 18. 

 f. 50. Fossil, America; recent from 

 sheU-cleanings. Front view with a nar- 

 row, smooth central zone; lateral sur- 

 faces not constricted beneath the slightly 

 prominent angles. 



T. acutum (E.). — Sides nearly straight; 

 angles elongated into points ; cellules not 

 radiating. Br MJ. i. p. 251, pi. 4. f. 16. 

 Bermuda. T. acutum is somewhat tri- 

 radiate from its acimiiuated angles. 



Doubtful or insufficiently hnown Species. 



T. scitulum (Br.). — "A small species, 

 but vaiying in size. On some of the 

 fi'ustules I have reckoned, on an end 

 view, about 45 cells only ; sides very 

 slightly convex; angles open. Diam. 

 1-350''." Br MJ. i. p. 250, pi. 4. f. 9. 

 Indian Ocean. Varies wdth foui' sides. 

 Except in its smaller size, we see not how 

 this species differs from T. Farus. 



T. Africanum (E.). — Sides convex ; 

 angles rounded; cellules large, in radi- 

 ating series. EM. pi. 35 b. 19. f. 1. 

 Eecent. West Africa. In form resem- 

 bles T. ohtusum. 



T. comptum (E.). — Sides straight, and 

 having a marginal fringe ; angles pro- 



longed into short, stout spines ; cellules 

 large, hexagonal. Eo MJ. ii. p. 283, f. 2. 

 England. "The cellular markings are 

 as large as in T. Favus, and I am rather 

 doubtfid whether it may not be a young 

 form of that species ; but the length of 

 the processes, and fringe-lilie row of cells 

 at the margin, appear to give it a di- 

 stinctive character " (Eoper). 



T. crassum (Sh.). — "Much smaller 

 than T. contortum. Is characterized by 

 the reticulations being coarse and irre- 

 gular in form, and the honis very large 

 as compared with the size of the valve." 

 Sh. in TMS. ii. p. 15. Natal. 



T. hyalinum (Br.). — " Small, trans- 

 parent, sm-face with very minute dots or 

 cellules; sides regular and straight." 

 Br M J. iv. p. 275, pi. 17. f. 16. Barbadoes. 

 = T. Reticulum. 



T. arcuaium.. — Sh T31S. ii. pi. 1. f. 5. 

 Natal. The figm-e resembles that of T. 

 Pileus, but without pseudo-nodides. It 

 is probably, however, the same. 



T. exiguum (Sm.). — Triradiate: angles 

 elongated into linear truncated pro- 

 cesses ; celkdes very minute, scattered. 

 SD. ii. p. 87; Br MJ. iv. p. 274, pi. 17. 

 f. 1. Fresh water. Ormsb3^ Norfolk. 

 (VI. 14.) 



T. Pentacrinus (Wallich). — Valves 

 slightly convex, with 5 angles, with 

 a short horn at each angle. Sm-face 

 spinous, divided into compartments by 

 anastomosing lines or costae, which radi- 

 ate irregidarly fi'om the centre. Var. /3 

 with 4 angles, y with 6 angles. A^'allich, 

 MJ. vi. p. 251, pi. 12. f. 10-14. St. 

 Helena. We scarcely see how this form 

 differs from Amjihitetras ornata of 

 Shadbolt. ^ 



T. duhium (Br.). — Valve minute, 

 clypeate, with 6 angles, the lower one 

 much produced; surface of valve coarsely 

 punctate. Br MJ. vii. p. 180, pi. 9. 

 f. 12. Mauritius, Californian gaiano, 

 India. " We place this form (which is 

 not of unfrequent occun-ence) provi- 

 sionally among the Triceratia. It pro- 

 bably forms the tvpe of a new genus " 

 (Br. /. c). 



T. Malleus, Br MJ. vi. p. 164, pi. 8. 

 f 6. Not Diatomaceous ? 



Genus AMPHITETEAS (Ehr.). — Frustiiles cellulose, cubiform, cohering 

 into a zigzag attached filament ; in lateral view quadrangular, -svith a pseudo- 

 opening at each angle. Since Mr. BrightweU's discovery of quadrangular 

 states of Triceratium, the only remaining distinction between that genus and 

 the present is, that in this the frustiiles form catenate attached filaments ; 

 but, according to Professor Bailey (as already noticed), even this character is 



