232 DESCRIPTION OF [Poiygastrica. 



boat-shaped Cocconema. — Lorica lanceolate, extremities 

 acute. Found with the preceding. Length 1-5 00th to 

 l-150th. 



333. Cocconema (?) (/ibbum {Cymbella, Agardh). The 

 gibbous Cocconema. — Lorica semi-oval, striated, and 

 slightly constricted at the ends ; branches spreading. 

 Found with the preceding. Length 1 -2300th to l-4S0th. 



334. Cocconema (?) fusidium. The spindle-shaped 

 Cocconema. — Lorica lanceolate, attenuated, nearly acute at 

 the ends, and smooth. Found, only fossil, with the pre- 

 ceding. Length 1-1 150th to 1 -620th. 



Genus LXXL Achnanthes. The standard Animal- 

 cules. — Lorica siliceous, simple, composed of two or more 

 pieces, form prismatic, longer than broad, and having a 

 central opening. In A. brevipes colourless stomach-cells 

 are visible ; the pedicle is simple, and its attachment 

 oblique and ventral. They are developed in the form of 

 simple pedicled chains (tablets or bands), which look like 

 little standards, longitudinal self-division commencing 

 beneath the glassy lorica. The members of this genus, 

 whether considered as animals or plants, present us with 

 the simplest examples of organic matter. They are para- 

 sitical on Algae, &c. 



335. Xcmsix^TH-Es longipes. The long- stalked Achnan- 

 thes. — Lorica striated, bent in the middle, dorsal and ventral 

 surfaces rounded, pedicle thick, and from two to five times 

 the length of the lorica. Found in sea-water. Length 

 (that is, breadth of band) 1-5 70th to 1-1 20th. 



336. Achnanthes brevipes. The short Achnanthes 

 resembles the preceding species, but the pedicle is much 

 shorter than the body, as shewn in fg. 199, 200, and 201, 



