Bacillaria.] THE INFUSORIA. 225 



of the water^ they were mostly arranged in a stellate form, 

 resting upon filaments of conferva. Size 1- 100th long, 

 1- 2000th broad. Dr. L. says, the lorica of those from the 

 Annan is not striated, nor are their ends dilated. (Proc. 

 Lin. Soc.) Sometimes they attach themselves to Vorti- 

 cella, as shewn in fig. 184, which represents several of 

 them thus situated; that marked by a cross is itself 

 infected by the growth of Podosphenia upon it ; so that 

 we have here an example of one parasite growing upon 

 another. Found both in fresh and brackish water. Size 

 l-280th to l-100th. 



305. SYNEDRA capitata. The broad-headed Synedra is 

 striated, straight, and of the form shewn at group 185*, 

 which exhibits a front and side view ; ova yellowish -green. 

 Found both living and fossil. Length 1-1 20th. 



306. SYNEDRA Gallionii (Diatoma fasti, Agardh). Gal- 

 lion's Synedra is smooth, wand-like, and attenuated late- 

 rally. The ova are in round clusters, arranged along the 

 lorica. It inhabits the sea. Length 1-1 20th. 



307. SYNEDRA fasciculata. The bundle-like Synedra is 

 smooth, attenuated near the extremities, and slightly 

 acute on all sides. Found attached to conferva. Length 

 1- 860th. 



308. SYNEDRA lunaris. The sickle-shaped Synedra is 

 smooth, curved, and associated together upon conferva, 

 as shewn in group 185. Length 1 -432nd. 



309. SYNEDRA bilunaris. The doubly -bent Synedra is 

 smooth, and resembles two lunate or crescent-shaped 

 bodies attached end to end. Found upon conferva. 

 Length l-570th. 



Genus LXVII. PODOSPHENIA. The wedge little plate 



Q 



