yai'iculacca.] iNFrsoRi.vL axtmalcules. 331 



apices elongated, tapering, rcciu'ved. Length l-o70th. Fresh 

 water. (P. 3, f. 147.) 



Ceeatoxeis s/;/>«^/.'?, (Kiitz.) — ]!^arrowly lanceolate, the flat beaks 

 sj)irally t\visted, and somewhat obtuse at the cuds. Length 1 -240th. 

 On the sea coast. (P. 16, f. 9.) 



Genus CnjEiocEKOs. — Concatenated ; lorica of two equal turgid 

 valves, with two apertiu'cs on each side, which, at the earliest period, arc 

 very shortly tubular when the corpuscles are contiguous, but are 

 afterwards produced as long cornua Avhen the corpuscles become 

 remote. The cornua become transformed ultimately into very long, 

 slender, and siliceous entangled threads. 



Tliese singular forms have a distant resemblance to Denticella ; and 

 individual corj)uscles have the habit of Peridinia. The filament- 

 like cornua, detached, may be mistaken for GaUionelloi. 



C. d'lchccta. — Each testule smooth ; the two horns of each side 

 often flexuose, and in course of time very long and liKform. 

 Diameter of each corpuscle, Avith the cornua, 1-11 o2ud. to 1- 720th. 

 Antarctic Sea. 



C. tetrachata. — Smooth ; horns four on each side, becoming very 

 long, and filiform. Diameter l-1152Tid. 



C. (?) Bacillaria. — ^Bacillar; breaath three to four times greater 

 than depth ; tnmcate at each end, and fiuTiished Avith two long 

 filiform cornua. Diameter 1 -864th. Bermuda. 



C. (?) Diploneis. — Constricted at the middle, rounded at each 

 end, with the habit of Diploneis, but with two filiform cornua from 

 each end. Diameter 1 -960th. Bermuda. 



The two preceding forms Avere fii'st observed and figm-el by 

 Dr. Bailey. 



C. didymus. — Smooth, width double its heighth, Avith two semi- 

 orbicular angular valves, almost of the character of Eiiastrum, Avith 

 two decussating filiform cornua fi'om the middle of each side. 

 Largest diameter 1-1 080th. Fossil in African Guano. Goniotheciimt 

 Gastridiiim found along with the preceding, may belong to the same 

 genus, but having, in its fossil state, its cornua broken off. 



Genus Coccoxeis. — The skield-Uke Navicida. Lorica bivalve, pris- 

 matic, or someAvhat hemispherical, Avith two apertures, one in the 

 z 2 



