Cryptomonadina.] the infusoria. 109 



59. Cryptomonas (?) fusca. The brown Crypto- 

 monas. — Oval, turgid, and of a Ijrov.n-colour. Found 

 amongst conferva. Size l-1500tli. 



60. Cryptomonas /en^icw/am. The lens- shaped Cryp- 

 tomonas — Form orbicular, resembling a lensj colour green; 

 lorica thick. Size 1-1 720th. 



Genus XI. Ophidomonas. Tlte serpent Monad. — The 

 distinguishing characters of this genus are its fihform bodj', 

 deficient of the eye, its smooth and obtuse lorica, and its 

 transverse but complete mode of self- dividing. It Avas 

 discovered by Ehrenberg in September, 1836. It is fur- 

 nished with a filiform proboscis, as its organ of locomotion, 

 which, together with the tubular lorica, and the numerous 

 digestive sacs, form the whole of the organization that has 

 hitherto been demonstrated. Its extremely small trans- 

 verse diameter is the great impediment to a better acquaint- 

 ance with this creature. Whether its brown- colour is 

 derived or not from the ova within it has not been de- 

 termined, nor has it been drawn. 



61. Ophidomonas Jenensis. The Jena Ophidomonas. 

 — Form very thin, curved spirally, and equally obtuse at 

 both extremities; colour olive-brown; motion brisk. Found 

 only at Jena, in well M'ater. Size l-S/Oth. 



Genus XII. Prorocentrum. The pointed shell Monad. 

 — The animalcules of this genus are destitute of the eye, 

 and have a smooth lorica, resembling a little box (urceolus), 

 pointed at the anterior extremity. They have a filiform 

 proboscis, for the uses previously described, and numerous 

 large digestive cells in the interior of the body. Self-divi- 

 sion has not been observed. " It is worthy of remark," says 

 Dr. Ehrenberg, " that the only species of this genus with 



