748 ORDER HYPOTRICHA. 



Genus III. LOXODES, Ehrenberg. 



Animalcules free-swimming, elastic, but persistent in form, more or less 

 elongate and lamellate ; the dorsal surface slightly convex, perfectly smooth 

 and naked, with a marginal border of short, hispid setae ; the ventral surface 

 furrowed longitudinally, clothed throughout with fine, even cilia ; oral 

 aperture ventral, subterminal, approached by a channel-like ciliated groove, 

 continued posteriorly into a tubular pharynx ; the walls of the pharynx 

 and adoral groove strengthened by a continuous sigmoidal or sickle-shaped 

 indurated membrane ; contractile vesicles numerous (?) ; endoplast com- 

 pound, racemose. 



Out of the numerous species formerly referred to the genus Loxodes by Ehrenberg, 

 Dujardin, and Perty, a single type only, L. rostrum, is now retained, the remainder 

 being referred in the majority of instances, by more modern investigators, to the 

 several genera Faramcecium, Aspidisca, C/iilodon, and Amphileptus. Engehiiann,* 

 who was the first to recognize the distinctive character of the dorsal and ventral 

 surface of the type form — the cuticle being described by Claparede and Lachmann 

 and all previous writers as evenly ciliate throughout — added to his detection of the 

 marginal border of set^, presumed he had an undescribed Infusorium under exami- 

 nation, and proposed for it the generic and specific title of Drepanostoma striata. 

 Its identity, however, with the Loxodes rostrum of Ehrenberg has since been 

 clearly demonstrated by Wrzesniowski,t and its entire structure most care- 

 fully worked out. As first intimated by Engelmann, the limitation of the cilia to 

 the lower surface, combined with the presence of the border of marginal setae, neces- 

 sitates the relegation of this type to the Hypotrichous section. Among these it 

 claims, with reference to the last-named structural characteristic, a relationship 

 with the setiferous Oxytrkhce, while with reference to the oral armature and character 

 of the ciliation, it more nearly approaches Chilodon. Through the genus Litonotus 

 of Wrzesniowski, Loxodes may be further said to retain its connection with the group 

 of the Holotricha with which, up to a recent date, it has been identified. 



Loxodes rostrum, Ehr. Pl. XLIL Figs. 1-3. 



Body very flexible, flattened, somewhat scimitar-shaped, about four and 

 a half times as long as broad ; the anterior extremity curved slightly to the 

 left and terminating in a beak-like point, the posterior extremity also 

 curving slightly inwards in the same direction, and angular on its left-hand 

 border ; the oral aperture debouching on the left side of the ventral surface 

 at a little distance from the apical extremity, a distinct adoral groove 

 produced from thence in an arcuate form to the apex of the anterior 

 beak-like point; the tubular pharyngeal cleft extending backwards in an 

 oppositely directed curve towards the right-hand border ; the walls of the 

 pharynx and inner surface of the adoral groove strengthened by a con- 

 tinuous brown-coloured, sickle-shaped, corneous induration, the posterior 

 or pharyngeal portion of which alone is tubular, this structure as a whole 

 extending to a distance of nearly one-third of the length of the entire 

 body from the apical extremity ; vibratile cilia distributed throughout the 

 longitudinal furrows of the ventral surface, those bordering the anterior 

 and posterior extremities most conspicuous ; a fringe of somewhat larger 

 * 'Zeitschrift fiir Wissenschaftliche Zoologie,' Bd, xi., 1861. ,t Ibid., 1870. 



