3o6 



ACTINELLA. 



C. Arcus Kiitz. (Baa, p. 104, pi. 6, f. 10; H.V.H. Atl., pi. 37, 

 f. 7* ; Type No. 281), plate 10, fig. 401. 



Characteristics of genus. Striae fine, delicately punctate, 16 or 17 in 1 

 c.d.m. Mean length, 5 to 7 c.d.m. Some specimens attain a much more 

 considerable length. 



Fresh water. Rare : Liresse, Rochehaut (Delogne), Liege (A. Verbeeck), Ard. Lieg. (De Wild.), 

 Westmoreland, England ; Arran, Scotland. 



GENUS 39. ACTINELLA LEWIS (1865). 



fi. 



Valves arcuate, furnished with terminal 

 nodules ; apices unequally developed, the 

 upper very strongly inflated in the form of a 

 club and furnished with a projecting point ; 

 the lower with a more feeble inflation, some- 

 times without any point. Margin of valve 

 level or undulated and furnished with coarse 

 beads and sometimes with small spines. 

 Striae delicate, punctate. Frustules parasitic, 

 grouped together, according to Lewis, in the 

 form of a star by the inferior apex. 



The genus Aitinella consists of American 

 diatoms, of which only four species have hitherto 

 been described. The Act. Gt(yanetisis Grim., 

 jBrasitiensis Gruti. and mirabilis are peculiar to 

 Brazil ; A. punctata Lew. belongs to North 

 America, but it has, however, also been found in 

 Norway. 



Fig. 70. 



Act. mirabilis (Eu/.) Gr. 



a. Entire valve. 



b. Upper and lower apices. 



Actinella punctata Lewis. (H.V.H. Atl., 

 pi. 35, f. 18 and 21*; Type No. 274), plate 30, 

 fig. 832. 



Small, clavate, with superior apex strongly emarginate ; the inferior apex 

 rounded, obtuse, scarcely inflated. Striae, about 17 in 1 c.d.m. Length, 

 about 8 to 11 c.d.m. 



Fresh water. A stream at Fisco, near Christiania, Norway (G. Norman, No. 529 ; in Coll. 

 Walker Arnott, No. 856 !). 



