320 ORDER FLAGELLATA-PANTOSTOMATA. 



to exhibit a remarkable peculiarity of deportment, which, though subsequently 

 observed, has not as yet been recorded of the preceding type. The adhesion in 

 these instances was effected only by the extreme distal terminations of the caudal 

 fiagella, and the animalcule, extended to its full length at their extremity, rotated 

 rapidly backwards and forwards on its long axis. The two caudal flagella were thus 

 alternately twisted upon each other in converse directions, while the four anterior 

 appendages performed, in unison with this reversible gyratory motion, graceful and 

 devious curves around the creature's body ; the aspect of an animalcule engaged in 

 such active exercise is represented at PI. XIX. Fig. 59. As already suggested by the 

 author in an article on " Parasitic Infusoria," contributed to the ' Popular Science 

 Review' for October 1880, it would seem highly probable that the form described 

 by Professor Leidy under the title of Trkhonympha agilis — referred provisionally in 

 this treatise to the Holotrichous order of the Ciliata — represents some species of 

 Hexainita, imperfectly observed by him under the conditions just related. The 

 simile invoked by this authority in connection with Trichonyinp/ia, that of ballet- 

 dancers having long cords suspended from their shoulders, which whirled around 

 them in mazy undulations as they danced, by no means inaptly represents the 

 characteristic aspect of the members of the present genus during their attached 

 gyratory phase of existence here recorded. 



The adhesive character of the caudal flagella of Hexamita is often manifested 

 by the animalcules picking up flocculent matter or other debris with these appen- 

 dages, and dragging it with them as they swim through the water. This pheno- 

 menon is indicated in the delineation by Stein, without explanatory notes, reproduced 

 at Fig. 58 of the plate just quoted, and has been frequently witnessed by the author. 

 In addition to its more ordinary sedentary condition, the present type has also 

 been observed by the author to creep and bore its way through the gelatinous 

 zoogloea-scum collected on the surface of vegetable infusions, the body at such 

 times assuming the most protean contours, and closely resembling that of an Amoeba. 

 Hexamita iiiflata is figured by Butschli as having six vibratile flagella, in addition to 

 the caudal pair, inserted at remote distances upon the lateral periphery. This 

 representation of their disposition is apparently derived from an error of interpreta- 

 tion, otherwise, if eight flagella in all were actually present, the example had evidently 

 developmented a supplementary pair, preparatory to the process of longitudinal 

 subdivision. Such an octoflagellate example, reproduced from Stein's volume, is 

 delineated at PI. XIX. Fig. 57 ; but in this case the supplementary pair is developed 

 at the posterior extremity, which has become doubly emarginate or quadrifid. 



Hexamita rostrata, Stein. Pl. XIX. Fig. 55. 



Body fusiform, broad and inflated centrally, with a conical or rostrate 

 anterior prolongation, and a still longer and attenuate caudal termination, 

 the total length about equal to twice the central breadth ; flagella long, 

 slender, and of equal size, the four anterior ones inserted close to each other 

 at the apex of the anterior prolongation, the two posterior appendages 

 similarly approximated at the end of the caudal extension ; contractile 

 vesicle posteriorly situated ; endoplast not indicated. Length 1-640". 



Hab. — Unrecorded. 



This species is shown by Stein's figures to correspond closely with H. intestbialis, 

 but may be distinguished from the same by the distinct prolongations of the anterior 

 and posterior regions of the body. In general contour, as delineated by Stein, this 

 type may be said to correspond singularly with that of the apterous insect Lepisma, 

 the proportions and locations of the two sets of flagella agreeing in a remarkable 

 manner with the antennary and caudal filaments of that arthropod. 



