524 ACTINOCYCLUS. 



at the centre of the valve, becoming finer and finer towards the margins, arranged 

 in radiating rows, forming undulated concentric circles ; about 8 puncta in 

 1 c.d.m. at the middle of the ray and 18 at the margin, where they are arranged 

 in quincunx. Diameter, 4 to 8 c.d.m. 



Marine. Blackenberghe, 2nd Basin, Scheldt at Antwerp (H.V.H.), England (W. Sm. ! 

 Hodgson, Kitton, Stolt. , Norman), Ireland (O'Meara). 



In the text of the " Synopsis " I have given the form under the following 

 descriptions : 



A. craSSUS (W. Sm. !) Ralfs {Eupodiscus crassus IV. Sm., 

 S.B.D., i., p. 24, pi. 4, f. 41*), plate 34, fig. 897. 



Mr. Rattray, in his Monograph, p. 154, says: "The present species is 

 separated from the Eupodiscus crassus of Smith, owing to the inconspicuous- 

 ness of the fasciculi and the sharpness of the submarginal zone." A further 

 examination has shown me that my form is quite identical with the authentic 

 gatherings, labelled by Wm. Smith himself, in my possession, but that Smith's 

 figure is faulty and shews fasciculi which do not exist in nature. Only in one 

 of the gatherings of W. Sm. at most can there be recognized, under low 

 magnification, a vague arrangement of puncta in radiating lines. I have 

 consequently modified the name of this in accordance with Rattray and 

 De Toni. 



A. Subtilis (Greg.) Ralfs. (in Pritch., p. 835; Eupodiscus 

 subtilis Greg. ; Diat. of Clyde, p. 29, pi. 3, f. 50 ; H.V.H. Atl., pi. 124, f. 7*, 

 Type No. 519, and var. Type No. 520), plate 23, fig. 661. 



Valve yellowish, almost hyaline, not iridescent ; pseudo-nodule submarginal, 

 less visible than the preceding species. Striae radiating, about 13 or 14 in the 

 middle of the ray, finely punctate, leaving hardly any subulate hyaline spaces. 

 Margins with small spines distant about 75^, with strire somewhat more 

 compact. Diameter of valve, 5 to 9 c.d.m. 



Marine. Not yet observed in Belgium. England, various localities (Weissflog, W. Arnott, 

 Kitton, Norman), Scotland (Greg.). 



A. Roperii (Breb.) Kitt. (Bull. Soc. Beige. Micr., 1878, p. 30; 

 Eupodiscus Roperii Breb. ; Coscinodiscus (?) ova/is Roper ; H.V.H. Atl., pi. 

 125, f. 5, 6*), plate 34, fig. 898. 



Valve greyish, rounded-elliptic, with margin furnished with a crown of 

 processes enlarged at the summit, striae delicately punctate, arranged in 



