EXPLANATION OF THE PLATES. 23 



Eunotia circus : 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. Gomphoncma 

 truncatum. 



PLATE XCIX. 



Fig. 1. Gomphonema acuminatum. — Fig. 2. Gomphoncma 

 dichotomum. 



PLATE C. 



Fig. 1. Gomphoncma cristatum. — Fig. 2. Gomphoncma Berhe- 

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

 nanthes minutissima. — Fig. 5. Achnanthes 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. Encyoncma pro stratum. 



PLATE CI. 

 Fig. 1. Cocconcma lanceolatum. — Fig. 2. Cocconcma cym- 

 biforme. — Fig. 3. Cocconcma Cistula. — Fig. 4. Cocconema 

 ventricosum. 



PLATE CII. 



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

 Fig. 2. : a, b, c. Frustalia viridis. — Fig. 3. Sphinctocystis 

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

 gibba. — Fig. 5. Navicula amjdiisbcena : a, front view ; b, 

 side view. — Fig. 6. Naviada platystoma. — Fig. 7. Navi- 

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

 Navicula phceniccnteron. — Fig. 10. Navicula Palea. — 



