Bacillaria.] THE INFUSORIA. 233 



which represent three groups, or banners, attached to old 

 Vaucheria. The clusters are sometimes many inches in 

 length. Fig. 202 is more magnified. Single specimens, 

 when laying on the ventral side, appear spindle-shaped, and 

 shew the oral opening in the middle. Found in salt- 

 water. Length l-860th to 1-1 80th. 



337. ACHNANTHES subsessilis. The narrow Achnanthes. 

 Lorica small, slender, slightly bent, and striated ; 

 pedicle short and thick. Found in fresh and sea-water. 

 Length 1-1 150th to l-430th. 



338. ACHNANTHES exilis. The delicate Achnanthes. 

 Lorica smooth (?) slender, and of a pale colour; pedicle 

 slender, often longer than body. Found on Conferva 

 rivularis. Length 1-1 150th to 1-5 70th 



339. ACHNANTHES minutissima. The dwarf Achnan- 

 thes. Lorica small, slender, and smooth ; pedicle length 

 of body. Found upon zygmena. Length 1- 1200th to 

 1 -800th. 



340. ACHNANTHES inequalis. The unequal Achnanthes. 

 Lorica unequally bent, and smooth. Found, fossil, in 

 Sweden. 



Genus LXXII. STRIATELLA. The zig-zag little standard 

 Animalcules have a simple siliceous lorica, square, or mostly 

 longer than it is broad, and without a central opening. 

 They are attached obliquely, by one extremity, to a short 

 pedicle, or foot- stalk, and are developed in the form of 

 little banners, one end of which often separates (gaping). 

 (See/#. 203.) The ova is at first dispersed in small masses, 

 which afterwards unite. 



341. STRIATELLA arcuata (Diatoma rigidum,D.C.) The 

 curved Striatella. Lorica tabular, nearly square, having 



