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. 226. 



7, Campilodiscus cli/peus. 8, Biddulpliia. 9, GallioneUa sulcata. 10, Trice-, 

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

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

 gilaria pectlnalis. 16, Meridian circniare. 17, Diatomaflncculosum. 



presenting a row of dots varying very much in number ; 

 minute strife 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 ribbou-liko 

 flinty case of Fragilaria pectinalis, which consists of 

 many bivalve segments : on the articulating surface there 

 are smg.ll grooves, represented in fig. 225, No. 15. A gin- 



