JOURNAL OF MICROSCOPICAL SCIENCE. 
DESCRIPTION OF PLATE XVIII, 
Illustrating Dr. Donkin’s paper on certain Species of Fresh- 
water Diatomacese. 
Fig. 
1. — Surirella Barrowcliffia, Donkin, a, S. V. b, M. Y. c, Frustule 
dividing, d, Oblique view of frustule. 
2. — „ subalpina, Donkin, a, S. Y. b, Oblique view of valve. 
3. — „ tenera, Greg. S. V. 
4. — Navicula Coquedensis, Donkin. S. V. 
5. — „ vernalis, Donkin. S. V. 
6. — „ Cymbula, Donkin. S. V. 
7. — „ limosa, Ktz. S. V. 
8. — „ firma, Ktz. S. V. 
9. — „ stauroptera, Ehr. S. V. 
