854 



SYSTEMATIC HISTORY OF THE rNTUSORIA. 



pseudo-nodules ; granules minute, radi- 

 ating from an angular umbilicus ; spines 

 few, marginal. Bri M J. iv. p. 275, pi- 17. 

 f. 17. Maryland deposit. There is at 

 each angle a short spine, and sometimes 

 another at the middle of each margin. 

 Professor Bailey regards this species as 

 identical with T. Amhlyoceros -, but we 

 cannot believe that Ehrenberg would 

 have omitted so remarkable a character 

 as the angular umbilicus, nor are both 

 species found in the same deposit. We 

 have already given our reasons for doubt- 

 ing the correctness of the supposition 

 that Ehrenberg foimded his Symholo- 

 phora Trinitatis upon this species. 



T. annidatum (Wallich). — Valve mi- 

 nute, with slightly produced rounded 

 angles and concave sides ; surface marked 

 with concentric rings, and a ray proceed- 

 ing from the centre towards each angle. 

 Ganges. WaUich, MJ. vi. p. 249, pi. 12. 

 f. 15. Valves covered with minute 

 puncta, aggregated into concentric rings. 



2 * Lateral surfaces with radiating 

 vein-like lines. 



T. radiatum (Bri.). — Sides straight ; 

 angles obtuse ; radiating lines most evi- 

 dent at centre and margin; granules 

 minute, radiating. Br. I. c. p. 275, pi. 17. 

 f. 14. Barbadoes deposit. Frustules 

 large, without horn-like processes. 



T. marginatum (Br.). — Valves ^dth 

 a triangular centre, which is surrounded 

 by a broad border divided into compart- 

 ments by short transverse lines. Br MJ. 

 iv. p. 275, pi. 17. f. 13. Fossil. Sides 

 straight, angles with double pseudo- 

 nodides ; granules of centre minute, 

 radiating, those of compartments larger 

 and scattered. 



T. venosum (Br.). — Sides concave ; 

 angles rounded, smface dotted, and 

 marked by three radiating pinnated lines 

 or veins, (vi. 17.) Br MJ. v. p. 274, 

 pi. 17. f. 5. Barbadoes deposit. A very 

 beautiful and distinct species. 



T. tahellarium (Br.). — Margin indented 

 in foliaceous curvatures ; granides nume- 

 rous near the margin, elsewhere in 

 patches; angles with small horns. Br 

 MJ. iv. p. 275, pi. 17. f. 15. Honduras. 

 This species is well distinguished by its 

 scolloped margin. It is doubtful whe- 

 ther it is properly placed in this section. 



T. variahile (Br.). — Surface with a 

 transverse line below each angle, and 

 f ome irregular radiating veins : granules 

 scattered, indistinct at the angles. Br 

 MJ. iv. p. 275, pi. 17. f 19. Peruvian 



guano. Resembles T. aUernans, but is 

 larger and generally distorted ; the angles 

 are conical. Mr. Brightwell figm-es a 

 quadrangular form of this species. 



T. truncatum (Br.). — Angles elongated 

 into broadly truncate arms, centre di- 

 vided into granulated compartments by 

 radiating vein-like lines. Br MJ. iv. 

 p. 274, pi. 17. f. 4. Barbadoes earth. 

 Frustules triradiate. 



3* Lateral surfaces with transverse lines 

 separating the angles from the hexagonal 

 centre. 



T. hrachiatum (Br.). — Trii*adiate ; an- 

 gles elongated into truncate arms, and 

 separated from centre by transverse lines. 

 Br M J. iv. p. 274, pi. 17. f. 3. Barbadoes 

 earth. Distinguished by its angles pro- 

 longed into rays. It resembles T. trun- 

 catum in form, but is smaller, and has no 

 radiating veins. 



T. aUernans (Bai.). — Sides straight, 

 angles obtuse, granulated like the hexa- 

 gonal centi-e. SBD. i. p. 26, pi. 5. f. 45. 

 Common, recent and fossil. England, 

 United States guano, (vi. 21.) Front 

 view quadrate, not constricted ; the 

 angles not prolonged into processes. 



T. trisulcum (Bai. MS.). — Sides very 

 concave ; angles broadly rounded, sepa- 

 rated from centre by transverse lines; 

 granules crowded and very minute at 

 angles, elsewhere few, large, and scat- 

 tered. (\t:ii. 27.) From a drawing by 

 Professor Bailey. Gulf-stream shells, 

 W. Indies. This species may be kno^vu 

 by its distant granides. 



T. castellatum (West). — Sides of the 

 frustule deeply concave ; angles forming 

 segments of circles. Valves with con- 

 cave sides and roimded angles, forming 

 dome-shaped eminences; surface pimc- 

 tate, with a single row of larger puncta 

 along the opposed margins. West, TMS. 

 viii. p. 148, pi. 7. f. 3. Barbadoes deposit, 

 (viii. 29.) 



T. Johnsoni (Ralfs, n.s.). — Valves with 

 rounded angles and concave sides, sm-- 

 face with scattered granules, and a large 

 granulated space at the angles, separated 

 by a transverse smooth band ; margin 

 with a few short lines. Barbadoes de- 

 posit. Johnson. Valves large, with 

 conspicuous gTanules, which are few at 

 the centre, and more numerous near the 

 margin ; each side with a few short strise 

 like those figured by Mr. BrightweU in 

 T. tahellarium, but the margin itself is 

 not undulated. 



T. umhilicatum (Ralfs, n.s.). — Valves 



