EXPLANATION OF THE PLATES. 23 



Eunotia arcus : a, front view ; b, side view. Fig. 6. 

 Eunotia diodon : a, front view ; b, side view. Fig. 7. Eu- 

 notia triodon : a, front view ; b, side view. Fig. 8. Eu- 

 notia tetraodon : a, front view ; b, side view ; c } oblique 

 view. 



PLATE XCVIII. 



Fig. 1. Gomphonema geminatum. Fig. 2. Gomphonema 

 truncatum, 



PLATE XCIX. 



Fig. 1. Gomphonema acuminatum. Fig. 2. Gomphonema 

 dichotomum. 



PLATE C. 



Fig. 1. Gomphonema cristatum. Fig. 2. Gomphonema Berke- 

 leyi. Fig. 3. Gomphonema minutissimum. Fig. 4. Ach- 

 nanthes minutissima. Fig. 5. Aclmantlies exilis ? Fig. 6. 

 Cymbella Arcus : a, front view ; b, side view. Fig. 7. 

 Cymbella turgida : a, a, front view ; b, side view. Fig. 8. 

 Cymbella zebra : a, front view ; b, side view. Fig. 9. 

 Podosphenia ? ocellatum. Fig. 10. Encyonema prostratum. 



PLATE CI. 



Fig. 1. Cocconema lanceolatum. Fig. 2. Cocconema cym- 

 biforme. Fig. 3. Cocconema Cistula. Fig. 4. Cocconema 

 ventricosum. 



PLATE CIL 



Fig. 1 . Surirella biseriata : a, front view ; b, side view. 

 Fig. 2. : a, b, c. Frustulia viridis. Fig. 3. Sphinctocystis 

 librilis : a, front view ; b, side view. Fig. 4. Navicula ? 

 gibba. Fig. 5. Navicula amphisb&na : a, front view ; b, 

 side view. Fig. 6. Navicula platystoma. Fig. 7. Navi- 

 cula ? nodosa. Fig. 8. Aulacocystis pellucida. Fig. 9. 

 Navicula phcenicenteron. Fig. 10. Navicula Palea. 



