333 Sketch of the Infusoria of the family Bacillaria. 



Fig. 7. Gomphonema , 7 a, another view of a frustule. Ma- 

 rine, Stonington, Conn. 



Fig. 8. Echinella flabellata, a single group. Fig. 8, &, a sketch of 

 several groups slightly magnified, drawn from the living specimen. Ma- 

 rine, Stonington, Conn. 



Fig. 9. Echinella , a group parasitic on an aquatic plant. Fig. 



9, a, h, different positions of a single frustule. Hudson River. 



Fig. 10. Cocconema , group supported on the branching pedi- 

 cel. Hudson River. 



Fig. 11. Cocconema , a, &, two positions of an individual sepa- 

 rated from its pedicel. 



Fig. 12. Achnanthes brevipes, several groups parasitic on a Con- 

 ferva; J, a larger pair; c, back view. Stonington, Conn., Hudson Riv- 

 er, &c. 



Fig. 13. Striatella arcuata. Marine, Stonington, Conn. 



Fig. 14. Naunema , a, J, two positions of the frustule separated 



from its tube. Marine, Staten Island, N. Y. 



Fig. 15. Naunema , a, frustule separate from its tube. Ston- 

 ington, Conn, 



Fig. 16. Naunema , a, &, two positions of a single frustule. 



Stonington, Conn. 



Fig. 17. Naunema , group of frustules within their tube. West 



Point, N. Y. 



Fig. 17, a. Naunema , single frustule. West Point. 



Fig. 18, a to d. Spiculse of Spongilla or fresh-water sponge. 



Fig. 19, a, h. Probably spiculse of another species of Spongilla. ^, 

 group of three individuals. 



Fig. 20. Amphidiscus rotula of Ehrenberg, probably derived from 

 a Spongilla. Fossil at West Point, near Boston, Wrentham, &c., also 

 in South America. 



Fig. 21 to 23. Siliceous bodies of organic origin, found with fossil 

 fresh-water infusoria. 



Fig. 24. Dictyocha fibula .? Ehr., common among fossil marine infu- 

 soria in the infusorial stratum of Virginia at Richmond and Rappahan- 

 nock cliffs. 



Fig. 25. Fragment of the preceding. 



Fig. 26. Dictyocha speculum, Ehr., with the preceding. 



Fig. 27 and 28. Siliceous bodies, found with the preceding. 



Fig, 29. Binary, triangular, siliceous bodies, found with the prece- 

 ding. 



Fig. 30 to 35, Siliceous spiculee, &c. probably derived from marine 

 sponges or Actinia, found with the preceding. 



Fig. 36. Scale showing yVV^s of a millimetre, magnified equally 

 with the drawings. 



