GENUS CEPHALOTHAMNIUM. 273 



thainnium cydopum. While readily adopting Stein's proposed generic designation, 

 the author's earlier conferred specific one is here retained. Superficially examined, 

 the dense clusters of this specific type, as first met with, presented a considerable 

 resemblance to the gregarious colonies of Deltomonas cydopum described on a 

 succeeding page. A nearer investigation, however, revealed the presence of the 

 common supporting stem or pedicle. In no instance was this supporting pedicle 

 found to exceed in height the length of a single animalcule's body, while in most 

 cases it scarcely attained to one half that altitude. While usually perfectly simple, 

 the larger colony-stocks occasionally exhibit a rudimentary branching of the pedicle 

 towards the summit, none so far met with by the author, however, presenting so 

 distinct a development of secondary branches as is indicated in Stein's figure repro- 

 duced at PL XVIII. 



Examined separately, the zooids of this species were found to present a consi- 

 derable range of variation in their form and general aspect, their component sarcode 

 exhibiting a more plastic or less firm consistence than in those of the Dendro- 

 monadidae previously described. Here, too, for the first time among the representa- 

 tives of this family group, examples were observed in which the flagella were entirely 

 retracted, and short pseudopodium-like processes projected from either one portion 

 or the general surface of the body. Phases of this amoebiform condition, as repre- 

 sented at PL XVII. Figs. 30 and 31, correspond in a remarkable manner with the 

 analogous amoebiform condition of the collared monad Codosiga botrytis delineated 

 at PL II. Fig. 25. This metamorphosed state is no doubt intimately connected with 

 the process of reproduction. The somewhat abnormal process of multiplication by 

 transverse fission, resulting in the product of a free-swimming zooid, was observed 

 on one occasion, and is represented at PL XVII. Fig. 32. This species has been 

 obtained by the writer attached to a species of Cydops taken from ponds on 

 Wandsworth Common. 



Cephalothamnmm cuneatum, S. K. PL. XVII. FIG. 12. 



Bodies subtriangular or cuneiform, compressed, attached in clusters of 

 about eight zooids to a slender, rectilinear, simple, or sparsely bifurcating 

 pedicle. Length of bodies 1-2500". 



HAB. Pond water, on a species of Cyclops. 



Examples of this species have been met with on one occasion only on the 

 Entomostracon mentioned, obtained from a pond near Acton. The most luxuriant 

 specimen presented only the single bifurcation of the pedicle, as represented in the 

 accompanying illustration. The larger size and more regular cuneiform contour of 

 the animalcules, combined with the comparatively greater and more symmetrical 

 development of the pedicle, distinguish this form from A. caspitosa with which it is 

 otherwise most nearly related. 



Fam. VI. BIKCECID^, Stein. 



Animalcules sedentary, ovate or pyriform, with a usually more or less 

 projecting anterior lip-like prominence, solitary or colonially associated, 

 secreting separate horny sheaths or loricae, which are mostly stalked ; 

 flagella terminal, two in number, one long and one short ; parenchyma 

 transparent ; no distinct oral aperture ; endoplast and one or more con- 

 tractile vesicles usually conspicuous ; increasing by transverse subdivi- 

 sion and by the separation of the body into a mass of sporular elements. 

 Inhabiting fresh and salt water. 



T 



