524 ORDER HOLOTRICHA. 



Amphileptus gigas, C. & L. Pl. XXVII. Fig. 68. 

 Body elongate-lanceolate, compressed or subcylindrical, attenuate pos- 

 teriorly ; the anterior trunk-like appendage equalling from one-fifth to one- 

 half or even the total length of the entire body, its inferior surface bearing 

 cilia of larger size, and enclosing throughout an even row of trichocysts ; 

 cuticular surface striate longitudinally ; pharynx conical, longitudinally 

 plicate ; contractile vesicles numerous, spherical, distributed throughout the 

 body-sarcode, frequently in a distinct row along the dorsal border ; endo- 

 plast band-like, S-shaped. Length 1-25" to 1-16." Hab.— Fresh water. 



This species, which was found in tolerable abundance by Claparede and Lach- 

 mann in the neighbourhood of Berlin, represents one of the largest known infusorial 

 forms ; the number of contractile vesicles possessed by a single animalcule, as 

 recorded by these authorities, approaches that of Trachelius ovum and Prorodon 

 margaritift'?-, pre\iously described, many being met with even in the anterior trunk- 

 like process. Wrzesniowski * has recently proposed to distinguish the two extreme 

 short and thick, and slender varieties of this animalcule, as encountered by himself 

 respectively at Grogec and Warsaw, by the subspecific names of Dilrptus (Amphi- 

 leptus) gigas grojccensis and D. {Amp/i.) gigas varsavicnsis. In the former of these the 

 proboscis never exceeds one-half of the length of the body proper, while in the second 

 and more attenuate form (see PI. XXVII. Fig. 68) this organ equals or even surpasses 

 the body in length. It was further observed by this authority that the short infundi- 

 bulate pharynx in the first-named variety was distinctly plicate, while in the second one 

 it was perfectly smooth. In no instance, even with the assistance of various reagents, 

 was Wrzesniowski successful in demonstrating the existence of a nucleus or endo- 

 plast in the numerous examples that fell under his observation ; the characters of 

 this structure, as given in the foregoing diagnosis, being derived from Claparede 

 and Lachmann's description. Wrzesniowski, on the other hand, records an instance 

 of multiplication by fission which was effected centrally in an oblique direction. 

 The habits o{ Afupkihpfus gigas, as attested to by the same observer, are essenti- 

 ally predatory ; living food only is appreciated, and consists chiefly of other 

 Infusoria, such as Stylcnychia histrio and 5. pustulata, and various Rotiferse. These 

 are seized and at once transferred to the oral aperture with the assistance of the pro- 

 boscis, as the animalcule pursues its way through the water. Its powers of natation 

 are highly developed and unceasingly employed, locomotion consisting chiefly of 

 swift progression in a straightforward direction, accompanied by rotation of the 

 body on its long axis, the proboscis meanwhile being thrust around in a tentative 

 manner in search of prey. As figured by Wrzesniowski, the contractile vesicles 

 are by no means so numerous as reported by Claparede and Lachmann, numbering 

 at the outside less than twenty, the greater portion of which are distributed in an 

 even row from one extremity to the other of the dorsal border. 



Amphileptus cygnus, C. & L. 

 Body lanceolate, compressed ; the trunk-like prolongation flattened, equal 

 to the body in length, bearing cilia of slightly larger size on its inferior 

 surface ; posterior extremity of body attenuately pointed ; contractile vesicle 

 single, spherical, of large size, situated near the base of the proboscis. 

 Length of body, including the trunk, 1-60". Hab. — Pond water. 



Amphileptus anas, Miill. sp. 

 Body elongate, subcylindrical, attenuate posteriorly ; trunk-like process 

 equal to one-half of the length of the entire body, thick and obtuse ; con- 



* "Infusorien von Warschau," 'Zeit. Wiss. Zool.,' Bd. xx., 1870. 



