24 P. T. CLEVE, ON DIATOMS FROM THE ARCTIC SEA. 



123. Grammatophora Islandica Ehb (Grun. Yerh. 186 

 pag. 418 var. / and ö) Spetsbergen Kings Bay (160 faths) A 

 sterdam Id., Danes Id. Finmarken Grötsiind. Greenland Da 

 vis Strait. 



i 



124. Rhabdonema Torelli Cl N. Sp. S. Y. lanceolate, gib- 

 bous in tlie middle, covered by strong costae united iu the 

 middle of the valve, thus forming two series of large, moré 

 or less irregular cellules. F. V. quadrate, with numerous 

 transverse costie (margins of the diaphragms). The entire sur- 

 face finely striate; striae composed of small granules. Dia- 

 phragms 10 — more with only one large opening in the middle. 



Length and thickness of de frustule 0,096 — 0,i4u m.m. 

 Strise 20 — 24 in 0,025 m.m. Cellulge 6 — 8 in 0,025 m.m. 

 Diaphragms 3 in O, o 2. 5 m.m. 



Greenland. Spetsbergen Waijgats Ids. rare. 



This very large and beantiful species bas some resemblance 

 with the R. robustum Grun (Verb. 1862, pag. 422, Pl. \'III, 

 fig. 1 a, b, c) but is distingiiished by its fine and regular strise, 

 composed of small granules. 



Pl. IV, fig. 20 a F.Y. b S.V. c »annulus». 



125. Rhabdonema arcuatum (Lyngb) Sm (Syn. II, pag. 34, 

 Pl. XXXVIII, lig. 305). Exceediugly common in the arctic 

 sea. Spetsbergen, Finmarken, Greenland. 



Striatella Crozierii Ehb. (M. G. Pl. XXXV A XXIII, fig. 

 14, 16) is in no respects distinct from K. arcuatum, but RTi. 

 Crozierii Pritch. is quite another species. 



Var. ventricosian Cl. X. Sp. S.V. gibbous in the middle; 

 strise fine about 25 in 0,o2 5 m.m. 



Length 0,0 5 m.m. Breadth 0,u3 m.m. (S.V.). 



Greenland Davis Strait. 



Pl. IV, fig. 21. 



Ehabdonema arcuatum occurs most abundantly in the 

 northern Atlantic. According to Grunow it has been found 

 also in the Mediterrauean sea, but I have never seen any 

 specimen from the tropical or southern seas. The Rhabd. 

 arcuatum Rab & Jan from Honduras (Beitr. pag, 12, Pl. III, 

 fig. 19) is certainly, if the figure be correct, another species 

 probably Rh. Crozierii Ealfs. in Pritch Inf. pag. 805, Pl. IV, 

 fig. 43. 



