142 DEscBiFTioN OF iPolygastvica. 



The genera liold the following relations : 



fForm short, self-tlivision ) r-T—t^-,--,,. 



Lorica obtuse J longitudinal or wanting ) t-rypiomonas 



and < 



J smooth Form long and toi'tuous ) rv„i,;,i„„, ™„» 



Eye absent i L Self-division transverse ] Opl^idomonas 



Lorica pointed anteriorly Prorocentrum. 



I 



'Lorica with a neck and narrow orifice Lagenella. 



Lorica an open shield ^ Orvnto^lena 

 (SfHii'lliinA LTyptogiena. 



Eye present 



Lorica with the orifice | (Scutellum) 



but no neck. 



I Lorica a closed box or ) ^ i, i „ 



I pitcher (tVc.o?«*) j Trachelomonas. 



" Of these genera," says Dujardin, "we accept but two, in 

 bringing together the Cryptoglena and Lagenella as subgenera of 

 Cryptomonas. Prorocentrum may be the same thing as our Oxyrrhis; 

 and we, moreover, unite with Trachelomonas, the genera Chcetotyphla 

 and Chcetoglena, placed by Ehi'enberg amongst the Peridinma. "With 

 respect to the genus Plxacus, it has been introduced among the 

 Euglena by this author, notwithstanding the difference existing in 

 the non-contractility of its integument. Lastly, oiu* genus JJiselmis 

 corresponds in part to the Chlamidomonas of the same writer." 



Since there is a general correspondence between the family Crypto- 

 monadina, of Ehrenberg, and that of Thecamonadina of Dujardin, we 

 may append the account of the general characters given by the latter 

 author of Thecamonadina. 



The species of this family are readily recognized by the stiffness 

 or inflexibility they display while swimming, or when brought into 

 contact with other bodies. The lorica of the Prorocentrum and 

 Lagenella is at once perceived to be a distinct covei-ing. When any 

 doubt, however, exists upon this point, a slight degree of pressure 

 in the aquatic live-box, or between two slips of polished glass, will 

 easily determine it. The lorica of the Trachelomonas is siliceous, 

 and indestructible by fire. 



Genus Ceyptomonas. The loricated Monads. — This genus is essen- 

 tially characterized (see the Table) by the species being destitute of 

 the visual organ, and having a lorica obtuse, or not attenuated 

 anteriorly. Body short, but not filiform ; self-division, if any, longi- 

 tudinal ; flagelliform filament very fine. 



Dujardin writes " In this genus Cryptomonas, I comprise all 



