96 Sketch of the Infusoria of the family Bavillaria. 
-Coscinodiscus patina. (Pl. 2, fig. 13, a. b.) Carapace large, 
* cellsof: moderate size disposed in concentric circles. Cells smaller 
towards the circumference. Fossil in chalk marl of Zante, alive 
at Cuxhaven. The young and vigorous specimens of live indi- 
viduals are completely filled with yellow granules, whilst the 
older ones have an irregular granulated mass within them. Di+ 
“ameter, ;3;th to ,3,th. Fossil at bier Va. Our fignte 
shows a small specimen. 
Of the genus Actinocyelus, Ehrenberg deaieiteds sivetibelh new 
species, which have been found fossil in the chalk marls of Oran, 
Caltasinetta, &e., and living in sea water at Cuxhaven, Chris- 
tiana and Tjérn. Several of these species haveno’ partitions, 
but have surfaces marked with minutely punctate rays. © The 
great variety which occurs among the forms of Actinocyclus, 
found fossil at Richmond, leave no doubt in my mind, that all 
of Ehrenberg’s species will be found among them. [I also be- 
lieve that I have seen a living species of this genus, or of Cos- 
cinodiseus, in the ooze of the Hudson River, near West Point. ~ 
For Ehrenberg’s characters for the new ee see ones 
Hist. Inf., p. 428-429. 
Naedibetsasas x 
Free, separate or binary, carapace simple, baci or i nibieliee 
(siliceous) having six [?| openings ; never united in form o a 
chain by perfect spontaneous division. 
On these characters as given by Ehrenberg for the genus Nae 
vicula, I would remark that there do not appear to be any true 
valves or parts capable of separation without fracture, although 
each species will usually break along certain lines or edges into 
a definite number of parts. Ihave not been able to satisfy my- 
self of the existence of six openings in N. viridis, (see remarks 
concerning that species,) and with regard to the species ever 
forming chains, I ean state that it is not rare to meet with four, 
sometimes even eight united laterally. I have even seen” them 
thus united in the fossil state. eg 
a. Having transverse strie, (internal cells, ) alr conlle: Suirivellas 
Navieula viridis. (Pl. 2, fig. 16; a, b.) Striate, eatapace etraights 
fifteen’ striae (cells) in-¢}yth of a. line. Length, g/g to 4 line: - 
This beautiful species is one of the largest sponser 
both in the recent and fossil state. It occurs all over Europe, and 
