FOSSIL INFUSORIA. 



437 



lanceolate shape, and a little indented on both margins ; 

 two of them have curved rows of dots, and the other two 

 are partly grooved with finer rows. Ehrenberg says they 

 have four openings, all on one side (fig. 225, No. 13), 



" ' Fig. 225. 



7, Campicodiscus ch/peus. 8, Biddnlphia. 9, Galhonvlia sulcata. 10, Trice- 

 r-itium, found in Thames mud. 11, Gomphonema geminatum, with their stalk- 

 like attachments. 12, Dietyocha fibula. 13, Eunolia. 14, Cocconema. 15, Fra- 

 gilaria pectinalis. 16, Meridion circulate. 17, Diatomaflocculosum. 



presenting a row of dots varying very much in number ; 

 minute -striae in some cases extend from each dot towards 

 the middle of the lorica ; and on the circumference there 

 are two of these dots. The spirals and the individual 

 lorica are very fragile, and therefore easily separated from 

 each other. Of a glistening whiteness is the ribbon-like 

 flinty case of Fragilaria pectinalis, which consists of 

 many bivalve segments : on the articulating surface there 

 are small grooves, represented in fig. 225, No. 15. A siii- 



