200 



E. Jargensen. 



Distribution: Balearic Isles. The main species known from 

 the coast of the isle of Skye. 



B. aurita (Lyngb.) Breb. 



Ci\ above p. 99. 



Probably derived from the plankton. 



Frequent: Stamsund -f-, Svolvser + c, Stene r +. 



Distribution: Cf. above p. 99. 



B. rhombus (Ehrb.) W. Sm. 

 \V. Sm. Brit. Diat. II. p. 49. pi. 45, f. 320. Dentkella r. Ehrb. 



i-ai-. trigona Cl. Van Heurck Synops. pi. 99, f. 2. 



Very rare: Svolv;er r. 



Distribution: Coasts of the North Sea and Western Europe. 

 Finmark (Cleve). 



B. turgida (Ehrb.) \V. Sm. 

 W. Sm. Brit. Diat. II, p. 50, pi. Ii2, f. 38. Van Heurck Synops. pi. 104, figs. 1, 2. 



Cerataulus t. Ehrb. 



Very rare: Svolvser rr. 



Distribution: Coasts of the North Sea and Western Europe. 



B. Smithii (Ralfs) V. H. 



Van Heurck Synops. p. 207, pi. 105, figs. 1—2. A. Schmidt Atlas pi. 116, 



figs. 5—6. Cerataulus S. Ralfs in Rritch. p. 847. 



Very rare: Moskenstrommen rr, Svolvaer r. 

 Distribution: Coasts of the North Sea and Western Europe. 

 Spitsbergen? (Cleve). 



B. antediluviana (Ehrb.) V. H. 

 Van Heurck Synops. pi. 109, figs. 4—5. Amphitetras a. Ehrb., Mikrogeol. 



pi. 21, f. 25 a— c. 



Rather frequent: Moskenstrommen +, Stamsund r, Kaftsund r, 

 Gaukvaero r, Stene r. 



Distribution: Common species, cosmopolitan; very rare, how- 

 ever, in arctic regions: Spitsbergen (it. Cleve). 



B. lata (Grev ). 

 Triceratium 1. Grev. Trans. Micr. Soc. 1865, p. 103, pi. 9, f. 20. A. Schmidt 

 Atlas, pi. 77, figs. 38—39. Amphitetras I. De Toni Syll. vol. II, sect. 3, p. 901. 



Very rare: Raftsund r. Very similar to the figures referred 

 to in Schmidt's Atlas. Side of the tetragone 67 |i. Marginal 

 pearls 5 on 10 \i; the rows of striae in the corners somewhat 

 radiating, 10 on 10 \>.. 



Distribution: Tropical species, according to De Toni (1. c.) 

 only known from Singapore and North Celebes. 



B. favus (Ehrb.) V. H. 

 Van Heurck Synops. pi. 107, figs. 1—4. Triceratium favus Ehrb. A. Schmidt 



Atlas, pi. 82, f. 2. 



Very rare: Raftsund, rr. Side of the triangle 92 |i; 2 areoles 

 on 10 \>-. 



Distribution: Rather common species, cosmopolitan on tropical 

 and temperate coasts. Spitsbergen (Cleve, „ doubtful as an arctic 

 species"). 



B. arctica (Brightw.). 



Triceratium a. Brightw. Micr. Journ. 1853, p. 250, pi. 4, f. 11. A. Schmidt 



Atlas pi. 79, figs. 12—13. 



Very rare: Stene r. 



forma baleena (Ehrb.). 

 Zygoceros b. Ehrb. Mikrogeol. pi. 35 A, XXIII, f. 17. Biddulphia b. Brightw. 

 Micr. Journ. VII (1859), p. 181, pi. 9, f. 15. Van Heurck Synops.pl. 112, f. 1. 



Very rare: Stene r. 



Distribution: Arctic regions. Vancouver; Cape of Good Hope 

 (De Toni Syll. p. 921). 



B. formosa (Brightw.). 



Triceratium f. Brightw. Grun. in Cleve et Grun. Arkt. Diat. pp. 111 — 112. 



A. Schmidt Atlas, pi. 79 f. 2. 



Very nearly related to the preceding species, from which it 

 differs chiefly in having the centre of the valve irregularly punctate, 

 not areolate, with scattered puncta smaller than the neighbouring 

 areoles. 



Very rare: Raftsund r. 



forma bala^na. 



Answering to the forma balcena of the preceding species. 

 Very rare : Kaftsund r. 



B. alternans (Bail.) V. H. 

 Van Heurck Synops. p. 208, pi. 113, figs. 4—7. Triceratium a. Bail. Micr. 



Obs. p. 40, figs. 55 — 56. 



Very rare: Stamsund rr. 



Distribution: Western Europe. West Indies. 



B. punctata (Brightw.j V. H. 

 Van Heurck Synops. pi. 109, f. 10 (forma 3-gona). Triceratium p. Brightw. 

 Micr. Journ. 1856, p. 275, pi. 17. f. 18, non Biddulphia punctata Grev. 1864. 



Very rare: Gaukvaero, rr. Irregularly punctate with puncta 

 very different in size, shape aud distance from each other, on an 

 average 5 on 10 |)-. Side of the triangle 40 \k 



Distribution: Tropical coasts of America, Africa and Asia. 

 The nearly related B. seutyta (Shadb.) V. H., which by De Toni 

 1. c. p. 944 is considered to belong to the same species, occurs in 

 Western Europe, the Skagerack. and the Mediterranean. 



B. nobilis (Witt.). 



Triceratium n. Witt. Diat. Simbirsk 1885, p. 34, pi. 10, f. 3; pi. 11, figs. 4, 7. 



A. Schmidt Atlas pi. 150, f. 25. Non Biddulphia nobilis Brun 1889. 



A specimen very similar to the figure referred to in Schmidt's 

 Atlas (from Archangel) was found: Gaukva?ro rr; Stene rr. 

 Large puncta, irregular in size aud shape, intermingled with minute 

 ones. Near the margin, larger areoles. In the centre, a con- 

 spicuous inward pointing spine is found. Side of the triangle 56 ().. 



A nearly related species is Triceratium Seibergii Grun., V. H. 

 Synops. pi. 112, tigs. 9 — 11 (from Mors). 



Distribution: Only known fossil from Simbirsk. Perhaps also 

 fossil in my samples (as is probably also the case with some of the 

 other species). 



