570 ORDER HOLOTRICHA. 



two authorities, a tolerably exhaustive knowledge of its structure and developmental 

 history has been arrived at. Some of the more important data thus placed on record 

 are herewith epitomized. Maupas, in his account of the circular sucker occupying 

 the depressed portion of the anterior extremity, and other details, states that the first- 

 named structure is formed by the retreat inwards of the wall of that broader surface, 

 which may be denominated the ventral one. The action of the sucker is compassed 

 by cords of sarcode which, starting from its inner wall, are attached to the opposite 

 or dorsal body-wall. The surface of the body is clothed with very close rows of 

 cilia. Four or five rows may be counted within the space of 01 mm. (1-2500" Eng.), 

 and in the concavity of the sucker they are half as numerous again. The cilia are 

 set very closely together about thirteen or fourteen in o i mm. They form the 

 only organs of locomotion, the progress of the animalcule being never very rapid. 

 The cuticle or ectoplasmic layer is composed of two distinct elements, the one external, 

 in which the prolongation of the cilia in the form of bacilli may be traced, while the 

 inner one is composed of transparent and apparently absolutely amorphous sarcode. 

 The cuticle is entirely destitute of contractility, the animalcule consequently being 

 unable to alter its form spontaneously. It is at the same time highly flexible and 

 elastic, allowing the body to become bent and to immediately regain its normal 

 contour on and after contact with external objects. The central endoplasm is com- 

 posed of clear liquid sarcode, having a peripheral layer of large opaque granules. 

 The nucleus or endoplast is free in the general cavity of the body, and is shifted 

 with the movements of the body from one extremity to the other. If a fresh endo- 

 plast, through rupture of the body, is brought in direct contact with the water, its 

 substance contracts, leaving, as in many other Infusoria, a fine, amorphous, superficial 

 membrane. The sinuous, canal-like, contractile vesicle, according to Maupas, is 

 provided with distinct walls a feature which, if correctly recorded, distinguishes it 

 from the structure bearing the same name found in any other Infusorium and com- 

 municates with the outer water by means of seven or eight lineally disposed, 

 clearly visible oval pores. The species propagates by multiple transverse segmentation. 

 The first stage of the reproductive process is accomplished through the appearance 

 of a clear band across the centre of the body. The endoplast, now occupying a 

 central position, and also the contractile vesicle, divides in two, and a constriction, 

 following the course of the clear band, separates the body into two equal halves, 

 which nevertheless remain organically united. This operation is repeated first 

 across the centre of each previously segmented moiety, producing four equal-sized 

 segments or quarters, and then again across the middle of each of these four new 

 subdivisions, thus producing an aggregate of eight equal-sized segments, which 

 ultimately become detached from each other, after the manner of the proglottids or 

 zoonites of a Cestoid worm. Phenomena closely coinciding with these just recorded 

 of Haptophrya gigantea have been already related of Anoplophrya prolifera. In this 

 last instance, however, it is only the posterior half of the body which undergoes 

 multiple segmentation. 



M. Certes' later investigations, while generally confirming the account given by 

 M. Maupas, have elicited some additional points of interest. It is more especially 

 noteworthy that he declares the anterior sucker-like organ to be, if not a true mouth, 

 at least an organ sui generis, wherein the first acts of nutrition are localized. The 

 thickness of the external cuticle added to the clear layer which separates it from the 

 internal body-mass, he considers sufficient to preclude all possibility of the pheno- 

 menon of endosmosis, though, on the other hand, he is inclined to believe that the 

 imbibition of fluid nutriment may take place through the thinner walls of the adhesive 

 disc. Upon these grounds M. Certes regards Haptophrya gigantea as supplying a 

 bond of union between the more typical entirely mouthless Opalinidae and the 

 ordinary stomatode Ciliata. 



Supplementary Species. 



An animalcule closely resembling Haptophrya gigantea in external contour was 

 obtained by M. R. Blanchard, in the year 1878, from the intestine of an Alpine 

 Triton. On examining preserved examples, M. Certes reports that they differ from 



