GENUS RAPHIDOMONAS. 391 



This animalcule is identified by Stein with both the Chtztotyphla armata and 

 C. aspera of Ehrenberg. As in many other species of the genus, the lorica presents 

 a wide range of individual variation, this being manifested most prominently in con- 

 nection with the more or less extensive development of the spinous processes. 



Trachelomonas caudata, Ehr. sp. PL. XXI. FIG. 24. 



Lorica elongate-ovate or flask-shaped, two or three times as long as 

 broad, tapering posteriorly and further produced into an acuminate tail-like 

 process, the anterior aperture developed in a neck-like manner, its free 

 margin everted and deeply toothed ; the entire surface, exclusive of the 

 anterior and posterior prolongations, finely and densely hispid. Length 

 1-864" to 1-480". Hab. Fresh water. 



This species is identified by Stein with the Chcetoglena caudata of C. G. Ehrenberg. 



Trachelomonas bulla, Stein. 



Lorica elongate-ovate, from two and a half to three times as long as 

 broad, produced anteriorly into a conical, neck-like prolongation ; the 

 surface entirely smooth or beset with minute hispid points which are both 

 finer and less thickly distributed than in T. hispida and T. caudata. Length 

 1-500" to 1-430". HAB. Fresh water. 



Trachelomonas acuminata, Schm. sp. PL. XXL FIG. 26. 



Lorica obovate or flask-shaped, inflated and widest posteriorly, supple- 

 mented in that region by an acuminate and somewhat irregular tail-like 

 process, the anterior extremity produced into a cylindrical, moderately 

 large, obliquely-truncate, neck-like prominence, the surface entirely smooth 

 throughout. Length 1-500". HAB. Fresh water. 



This animalcule was originally described by Schmarda under the title of Lagenella 

 acuminata, and is refigured and referred to the present generic group by Stein. 



Doubtful Species. 



Pritchard's ' Infusoria ' includes the briefest possible diagnosis of two additional 

 species of Trachelomonas as follows, and without any reference to their original 

 describers : 



" T. areolata, globose, surface areolated. 



" T. aspera, similar to the preceding, but its surface covered with rough points." 



GENUS VI. RAPHIDOMONAS, Stein. 



Animalcules free-swimming, monoflagellate, moderately contractile ; oral 

 aperture terminal, conducting to a well - defined pharyngeal chamber ; 

 cuticular layer enclosing a large number of variously distributed trichocysts ; 

 contractile vesicle and endoplast conspicuous ; colour green. 



This genus is founded by Stein on the Monas semen of Ehrenberg ; excepting 

 for the presence of numerous and variously distributed trichocysts it closely 

 resembles Ccelomonas. 



