TRANSACTIONS OF MICROSCOPICAL SOCIETY. 
DESCRIPTION OF PLATES XI & XII, 
Illustrating Dr. Greville’s paper on New Diatoms. 
Series XX. 
Fig. 
1.—Plagiogramma elongatum, front view. 
2.— * valve. 
3.— a angulatum, front view. 
4.—Cestodiscus Stokesianus. 
5.— pulchellus. 
6.—Aulacodiscus sparsus. 
1.—Gephyria gigantea, \ower valve, frout view. 
§.— s 5 valve, side view. 
9.—Rutilaria elliptica, front view. 
10.— w a valve. 
11.— 5, superba, front view. 
12.— ~ » valve, side view. 
13.—Cocconeis armata. 
14.—Omphalopelta Moronensis. 
15.—WNavicula excavata. 
16— ,, Sgyptiuca, front view. 
Wi 3 = side view. 
18,19.— ,,  permagna, very large, from Berbice. 
20.—  ,, 3 small var., from Berbice. 
2h—"- v,, re var. from Delaware River, U.S. (out- 
line of Dr. Lewis’s figure). 
22.— ,, Zanzibarica. 
93— =, Jamaiceasis. 
Q24.— strangulata. 
2.—  ,, rimosa. 
All the figures are x 400 diameters. 
