22G DESCRIPTION OF [Pohjgastrica. 



Animalcules. — Infusoria with a simple, siliceous, wedge- 

 shaped (cuneiform) lorica, attached, when young, (by a 

 little pedicle, or none,) but often becoming free at a later 

 period ; longer than broad. The bivalved lorica has two 

 openings at its broad anterior end ; ova yellowish-green. 

 When young, they are scattered, but united into one or 

 two masses (often star-shaped) when old. According to 

 Ehrenberg, spontaneous longitudinal self- division is 

 common. Fragments of Meridion and Echinella are 

 liable to be mistaken for this genus. 



310. PoDOSPHENiA gracilis. The slender Podosphenia 

 has a smooth wedge-shaped lorica, as shewn at fig. 186, 

 which is a group of them attached to a thread-like fila- 

 ment, from which they are often mistaken for Echinella ; 

 ])ut in this case the filament is not part of the creature, 

 but merely the substance to which it has adhered. In 

 this way it often covers Algae, Vorticella, Sertularia, &c. 

 At the lower part of the group, towards the right side, is 

 represented a side view of one laying across two others, 

 shewn in front view; in the latter, delicate longitudinal 

 striae are visible, and in the former the upper part of the 

 lorica is rounded. Length 1 -250th to 1-1 10th. 



311. Podosphenia abbreviuta [Licmophora, Agardh). 

 The rhomboidal Podosphenia is smooth, broader and 

 shorter than the preceding. Found upon Ceramium 

 diaphonum. Length 1 -240th. 



312. Podosphenia cuneata {Frustulia, Agardh). The 

 broad Podosphenia is striated, laterally ; it is i-homboidal, 

 club-shaped, and slightly pointed. Found in salt water. 

 Length 1- 140th. 



313. Podosphenia? nana. The dwarf Podosphenia is 



