GENUS SYNURA. 4 1 1 



occupying the anterior half of the cavity of the lorica, attached to the side- 

 wall of the same by a thread-like prolongation of the posterior region ; 

 primary flagellum exceeding the body in length and three times longer 

 than the secondary one ; eye-like pigment-spot conspicuous ; contractile 

 vesicle situated a little in advance, and the endoplast a little to the rear of 

 the centre of the body. A large, subspheroidal, fat-like amylaceous cor- 

 puscle located near the posterior extremity. Length of loricae, 1300". 

 HAB. Fresh water. 



The great proportional length and attenuate posterior terminations of the loricje 

 of this species, as figured by Stein,* distinguish it conspicuously from the preceding 

 type. This elongate outline of the posterior region is so marked as to almost 

 acquire the character of an independent pedicle, while the contour of each inde- 

 pendent lorica, as a whole, may be appropriately compared with that of a post-horn. 



Dinobryon juniperinum, Eichwald. PL. XXII. FIG. 23. 

 Cells of polythecium evenly ovate or fusiform, not everted at the anterior 

 border but tapering equally towards each extremity, joined to one another 

 without the intermedium of a stalk-like prolongation ; the entire colony 

 consisting of a straight median line of the constituent cells, from the 

 anterior borders of each of which three cells originate, one directed straight 

 forwards and continuing the main rachis, and one other on each side of this 

 median one, which become further developed into oblique lateral branchlets, 

 these latter subdivisions frequently giving rise to secondary oblique off- 

 shoots. HAB. Fresh water. Dimensions unrecorded. 



The compound polythecium of this species only is figured and described by 

 Eichwald in his ' Infusorienkunde Russlands,' 1847, no reference being made to the 

 inhabiting animalcules. The evenly ovate shape of the individual cells and the 

 symmetrical rectilinear mode of growth of the general colony, distinguish it in a 

 marked manner from D. sertularia. 



Doubtful Species. 



A description of two additional species of the genus Dinobryon is included in 

 Pritchard's ' Infusoria,' p. 547, the characteristics of which, however, as here repro- 

 duced, are almost too vague for reidentification. 



Dinobryon (?) sociale, Pr. " Small ; enveloped in a shell of a simply 

 conical shape, truncated at the mouth. Developed in the form of a shrub- 

 like polypary. In fresh water. 1-860" ; cluster 1-280"." 



Dinobryon gracile, Pr. Less branching (fruticose), lorica slightly con- 

 stricted at the middle, aperture truncated. Animalcule 1-2080". 



The Dinobryon petiolatum of Dujardin is transferred by the author of this treatise 

 to De Fromentel's genus Stylobryon, and is evidently identical with both the 

 6". insignis of that writer and with the Poteriodendrum petiolatum of Stein. 



GENUS XIII. SYNURA, Ehrenberg. 



Animalcules free-swimming, united in subspheroidal social clusters, 

 each zooid contained in a separate membranous sheath or lorica, the 

 posterior extremities of which are confluent ; flagella two in number, 

 * ' Infusionsthiere,' Abth. iii., 1878. 



