coscinodiscus. 533 



Valve circular, margin not spinous, alveoles small, easily seen to be puncti- 

 form, arranged in fasciculate rows. 



Marine. 



This type-form is represented in our region by the following varieties : 



var. Normanii Greg. (Coscinodiscus fascicu/atus, A. Sclun. ; Coscino- 

 discus siibtilis, Eul., No. 115; H.V.H., pi. 131, f. 1*), plate 23, fig. 668. 



Valve without spines, alveoles small, very small at the margin ; rows of 

 alveoles bifurcating so as to form, near the margin, fascicules, consisting 

 of 6 rows; near the margin, 9 rows of alveoles in x c.d.m. Diameter of 

 valve, 3 - 5 to 7 c.d.m. 



Marine. Frequent. Blankenberghe, Antwerp (Scheldt, H.V.H.). Hull, England 

 (Norman). Ireland (O'Meara). Holstein (Moller) 



var. Rothii Grun ! (Cose. Rothii Grun., Kasp. Meer, p. 28; H.V.H., 



Types Nos. 532 and 533). 



Valve small, with margin furnished with small spines placed just at the 

 middle of the fasciculi ; about 12 stria? in 1 c.d.m. at the margin of the 

 valve. Diameter, 2*5 to 3*5 c.d.m. 



Marine. Antwerp, very frequent in the Scheldt 



C. laCUStris Grun! (Diat. Fr. J. Land, p. ^, pi. D, f. 300; 

 Cyciotclla punctata IV. Stn.; H.V.H. Ati. Suppl., f. 42*; in Type No. 535), 

 plate 23, fig. 669. 



Valve orbicular, undulated at the side, with margin furnished with small 

 spines, approximate (6 in 1 c.d.m.), and very distinct. Puncta fine, arranged 

 in radiating rows, divided dichotomously. About 10 to 11 rows in 1 c.d.m. 

 at the margin of the valve. Diameter, 1*5 to 6 c.d.m. 



Fresh water. Deurne, near Antwerp (P. Gautier). England: Market Weighton (Norman, 

 Grunow), Yorkshire, Wisbeach (W. Sm.), Breydon (Kitton). 



C. punCtulatUS Greg. (Diat. of Clyde, p. 28, pi. 2, f. 46*), 

 plate 34, fig. 904. 



Valve with radiating striae, very fine (about 20 to 22 in 1 c.d.m.), scarcely 

 visible towards the centre of the valve, intermixed with coarse scattered 

 puncta. Margin striate and clearly defined. Diameter, 4-5 to 8-5 c.d.m. 

 Marine. Lamlash Bay and Loch Fine, Scotland (Greg.), Ireland (O'Meara). 



Note. Gregory has referred this form to the Coscinodiscus with doubt, and 

 believes that it may be a valve of Meiosira. Walker Arnott in his manuscript 



