1888 - 89 .] Mr John Rattray on the Genus Coscinodiscus. 581 
C. lacustris. Grun., Kongl. Sv. Vet. -Ah. Handl. Stochh ., 1880., 
No. 2, p. 114. — Circular or elliptical. Diam. *035 to *075 mm. 
Surface with a slight unilateral undulation close to the centre. 
Central space and rosette absent. Markings minute, 6 to 10 in *01 
mm.; rows radial, non-fasciculate, most distinct about semiradius; 
a circlet of minute apiculi, about 6 in *01 mm., close to the border, 
within these a few scattered irregularly placed, hut similar apiculi 
forming an indistinct inner circlet. — Grun., Denh. Wien. Ah ., 1884, 
p. 85, pi. iv. (D), fig. 30; Van Heurck, Syn. Diat. Belg ., pi. c. 
fig. 42; Cleve and Moller, Diat., No. 172; Yan Heurck, Typ. 
Syn. Diat. Belg., No. 535 ; Kitton, Norfolh Diat., Nos. 3, 21 ; 
Cyclotella punctata, W. Sm., Syn. Brit. Diat., ii. p. 87 ; Stephano- 
discus pundatus, Grun. 
The name pundatus of Smith cannot be retained, because of 
Coscinodiscus pundatus, Ehrb., which is a distinct species. 
Distinguished from C. capensis by the absence of a central space 
and the irregularity of the inner circlet of smaller apiculi, and 
from C. plicatulus by the more delicate markings and the nearer 
approximation of the circlet of apiculi to the border. 
Habitat. — Kara Sea, Jamal (Cleve ! Grunow) ; Market Weighton, 
England (Grunow) ; Locality (?) (Kinker !) ; Yorkshire (Yan 
Heurck!) ; Wisbeach (S. Smith !) ;* Breydon (Kitton !). 
Yar. septentrionalis. C. (lacustris, var. ?) septentrionalis, Grun., 
ibid., 1884, p. 85, pi. iv. (D), figs. 28, 33. — Diam. *0365 to *055 mm. 
Surface with a short central transverse plication, most pronounced 
at the centre. Markings larger, 8 to 9 in *01 mm., decreasing 
somewhat near the border ; apiculi closely placed, arranged in a 
single circlet near the border. 
Grunow has found specimens at Cuxhaven and in the Gulf of 
Bothnia, intermediate between this var. and the type. 
Habitat, — Franz Josefs Land, Kara Sea, Jamal, Cape Wan- 
karema (Grunow) ; Canton River, Whampoa (Grove !) ; Balearic 
Islands (Cleve !). 
Yar. hyperborea. C. ( lacustris , var.?) hyperboreus, Grun., ibid., 
1884, p. 85, pi. iv. (D), fig. 26. — Diam. *037 mm. Undulation 
near the centre faint. Markings angular, 10 in *01 mm.; subepual 
* In the 'collection of W. Smith. 
