TEXTILARIA TROCHUS. 151 



Textularia teochus, Vanden Broeck, 1876. Ann. Soc. Belg. Microsc, vol. ii, 



p. 132, pi. iii, figs. 11, 12. 

 Goes, 18S2. K. Svensk. Akad. Hand!., vol xix, p. 80. 

 (PI. v, figs. 153—158, referred by Dr. Goes to 

 T. sagittula, appear to belong to T. trochus.) 



— — Brady, 1884. Keport 'Challenger,' p. 3t>G, pi. xliii, tigs. 



15—19; pi. xliv, figs. 1—3. (Limbate or 

 lipped.) 



— Agassiz, 1888. Cruises ' Blake,' vol. ii, p. 105, tig. 501. 

 Terrigi, 1889. Atti Lincei Mem., ser. 4, vol. vi, p. 18, 



pi. v, fig. 1. (Chambers flatter ; shell 

 neatly conical.) 

 — Burrows, Sherborn, and Bailey, 1890. Journ. R. Micr. Soc, 



p. 553, pi. viii, fig. 14. 



— — Haeusler, 1890. Abhandl. Schvveiz. Pal. Ces., p. 72, pi. xi, 



figs. 43, 44. (Very broad and flat.) 



— — Chapman, 1892. Journ. Micr. Soc, p. 328, pi. vi, fig. 18. 



— — Egger, 1893. Abhandl. k. Ak. Bayer., vol. xxviii, part 2, 



p. 273, pi. vi, figs. 37, 38. (With lipped 

 or limbate chambers.) 



— — de Amicis, 1893. Boll. Soc. Ceol. Ital., vol. xii, pp. 50, 



180, 181, 340. 



Characters. — Shell short, conical, trochoid, sides rounded; anterior surface 

 circular, and flat or concave. Sutures but little, if at all, excavated. Chambers 

 horizontal, uarrow. Texture variable, often rough. This is one of the most 

 symmetrical of the Textilarise. 



The only feature by which this species may be distinguished from short 

 specimens of T. sagittula is its circular contour ; and though the amount of 

 compression in the latter species is, as might be supposed, a very variable 

 character, T. trochus still represents a tolerably well-defined group. D'Orbigny's 

 figure is a somewhat idealised representation of the shell, and indicates a much 

 neater and more compact build than is usually seen in nature. 



Plecanium Speyeri, Reuss, 1864, ' Sitzungsb. Ak. Wien,' vol. 1, p. 440, pi. i, 

 fig. 3, conical, slightly compressed, with horizontal chambers, is near T. trochus. 



Occurrence. — Textilaria trochus has a wide geographical range, and is 

 particularly abundant amidst coral sands of tropical and subtropical latitudes. It 

 is a common Cretaceous fossil, — the species was originally described by d'Orbigny 

 from the White Chalk of the Paris Basin. Its range has lately been shown to 

 extend from the Neocomian (Bargate Beds) of Surrey (Chapman). Other localities 

 from which it has been obtained are the Gault of Folkestone, the Red Chalk of 

 Speeton, the Chalk-marl of Charing (where the species is particularly well 

 developed), the Upper Chalk of Taplow, the Pliocene of Garrucha, and the 

 Pleistocene of Sicily. We have specimens from the Miocene of Muddy Creek, 



