OF THE AXGrLIFEKEiE. 



855 



witli broadly rounded angles and deeply 

 sinuated sides, triangular smooth um- 

 bilicus, radiant series of close granules, 

 and a large punctate space at each an- 

 gle. Barbadoes deposit. Johnson. This 

 large and beautiful species is distin- 

 guished by the sinuated sides and tri- 

 angular umbilicus of the valves. Gra- 

 nules conspicuous and dense, appearing 

 both radiant and concentric. The large 

 angles are separated by indistinct trans- 

 verse lines, and appear smooth or granu- 

 lated according as they are more or less 

 in focus, and they have a central round 

 spot (probably a process) and sti-iated 

 margin. This species diifers from T. 

 castellatum in a distinctly radiant ar- 

 rangement of the granules and a smooth 

 mnbilicus. 



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

 angles obtuse, with pseudo-nodides, and 

 separated by transverse lines from the 

 hexagonal centre. EM. pi. 35. In guano. 

 Small, somewhat resembling T. Reticulum, 

 but diifering in its pseudo-nodules and 

 hexagonal centre. 



4* Sides in lateral view (/ibbous or un- 

 dulate {angles without pseudo-nodules; 

 cellules minute). 



T. undalatum (E.). — Sides slightly 

 convex, undidated ; granules minute, 

 radiating. Br MJ. i. p. 250, pi. 4. f. 13 ; 

 ERBA. 1840, p. 273. Fossil. Bermuda 

 and Virginian deposits. 



T. Brightivellii (West). — Sides of 

 valves undulate, slightly convex, or 

 straight ; granules minute, radiating 

 from the centre, from which proceeds a 

 spine of considerable length ; margin of 

 valve closely set with short spines. = T. 

 uadulatum, Br MJ. vi. p. 154, pi. 8. 

 f. 1-5, 8 ; West, TMS. viii. p. 149, pi. 7. 

 f. 6. Var. i3 with 4 angles. In Noctilucae. 

 England. The discovery of this and the 

 following species in a living state has 

 explained the appearance of the central 

 pseudo-nodule, which has proved to be 

 the remains of a long horn or spine. 



T. intricatum (West). — Sides of valves 

 undulate ; angle acute and slightly pro- 

 duced ; centre tumid ; granules in lines, 

 radiating from the centre, scarcely dis- 

 cernible ; pseudo-nodule apparent. = T. 

 striolatum P, SBD. i. p. 27, pi. 5. f. 46 ; T. 

 undulaium, Bri. /. c. ; West, TMS. viii. 

 p_. 148, pi. 7. f. 5. This species in its 

 living state forais short filaments united 

 in a distant series. 



T. striolatum (E.). — Sides convex, 

 slightly undulated; angles attenuated, 

 ending in minute papiUee. KB. t. 18. 



f. 10. = T. mc7nhranaceum, Br MJ. i. pi. 4. 

 f. 15. Thames mud, Cuxhaven. Walls 

 of the frustule extremely delicate, dotted 

 over with very minute cellules. 



T. Parmula (Br.). — Sides gibbous, 

 with produced mammiform angles ; sur- 

 face minutely punctated. Br MJ. iv. 

 p. 275, pi. 17. f. 2. Natal. Var. /3 with 

 4 angles. West, TMS. viii. p. 147, pi. 7. 

 f. 1. Frustules minute, in outline re- 

 sembling a shield. 



T. Americana. — Sides convex, slightly 

 undidated ; angles rounded ; cellules 

 minute. = T. Amhlijoceros ?, Br MJ. i. 

 p. 250, pi. 4. f. 14. Fossil. Richmond, 

 Virginia. The roimded angles without 

 appendages distinguish this species from 

 the others in this section. 



T. margaritaceum (Ralfs, n. s.). — 

 Valves with rounded angles, and straight 

 or slightly convex sides ; smface with 

 conspicuous pearly granules, which are 

 scattered at a triradiate central space, 

 and arranged in radiating lines at the 

 margin. Barbadoes deposit. Johnson. 

 The valve is bordered by a row of larger 

 gi'anules ; and only a narrow inconspicu- 

 ous temiinal portion of the angles appears 

 smooth. 



T. gihhosum (Harv. & Bail.). — ^^Almost 

 inflato-globose, the sides very convex, 

 angles prominent ; sm-face marked as in 

 T. concavum.'''' Small. Proc. of Acad, 

 of Nat. Sci. Philadelphia, 1853. Tahiti. 



5* Frusttdes not spijious, sulcate, veined^ 

 nor undulate. 



t Cellules large, hexagonal. 



T. Favus (E.). — Sides straight or 

 slightly convex ; angles obtuse, with 

 horn-like processes ; surface reticidated 

 with large hexagonal cellules, (xi. 43, 

 U::) = T.meqastomum,'Bv'SU. i. pi. 4. f.7?; 

 T. fmhriaium, WaUich MJ. vi. p. 247, 

 pi. 12. f. 4-9. Recent and fossil, not 

 uncommon. Diam. 1-200'' to 1-150". 

 Front view ^vitll the central portion mi- 

 nutely pimctated, the lateral portions 

 scarcely constricted beneath the short 

 stout processes. Mr. Brightwell figures 

 a quadi-ilateral form of this species with 

 concave sides. 



T. serratum (Wallich). — Valves (qua- 

 diilateral) furnished Avith a hom-like 

 process at each angle, and from 4 to 6 

 elongated scattered spines, with furcate 

 apices ; sides or plates of connecting zone 

 joined bv dovetailed margins. Wallich, 

 MJ. vi. p. 243. pi. 12. f. 1-3. St. Helena. 

 Connecting zone as well as valves marked 

 with a delicate but well-denned hexa- 



