GENUS DENDROMONAS. 265 



flagella two in number, one long and one short ; endoplast and one or more 

 contractile vesicles usually conspicuous ; no distinct oral aperture, food being 

 incepted at all parts of the periphery. Inhabiting fresh water. 



The representatives of this genus differ only from those of Physomonas, in that 

 the resultants of division by longitudinal fission, instead of being cast off as free- 

 swimming animalcules, remain adherent by their slender thread-like pedicles, and 

 which, taken in the aggregate, present necessarily a more or less regular dichotomous 

 plan of growth. 



Cladonema laxa, S. K. PL. XVII. FIGS. 5-7. 



Bodies irregularly pyriform, compressed, the anterior border widest, 

 obliquely truncate; attached separately to the extremities of a slender, 

 flexible, thread-like, irregularly-dichotomously branching pedicle ; con- 

 tractile vesicle posteriorly located ; endoplast spherical, subcentral. Length 

 of bodies 1-3250". 



HAB. Pond water, on Myriophylhim. Colony-stocks including from 

 three or four to as many as twenty or more zooids. 



This species was first briefly described by the author, with an accompanying figure, 

 in the ' Monthly Microscopical Journal ' for December 187 1, under the title of Antho- 

 physa laxa; the isolated instead of clustered mode of attachment of the animalcules 

 to their pedicle, added to the flexible, thread-like aspect and consistence of this 

 structure, distinguishes it, however, so conspicuously from the representatives of 

 either the genus Anthophysa or other allied forms described in this treatise, that a 

 new generic title has been created for its reception. Except for the somewhat more 

 elongate contour of their bodies, the colony-stocks of the present form might be 

 aptly compared to a number of zooids of Physomonas socialis, with their flexible 

 thread-like pedicles intimately united. The process of multiplication by longitudinal 

 fission, as shown at PI. XVI. Fig. 6, and also that of the ingestion of solid food- 

 particles at various points of the periphery, may be observed with great facility in the 

 somewhat large and distinctly isolated zooids of this species. At Fig. 7 of the plate just 

 quoted, an example is given of food-inception towards the posterior region of the 

 lateral border. As originally figured and described, this species was reported as 

 forming colony-stocks of three or four zooids only. More luxuriant examples, 

 including as many as twenty or more animalcules, remitted by Mr. Thomas Bolton, 

 of Birmingham, have, however, since been examined, and have supplied the material 

 for the accompanying illustration. 



GENUS III. DENDROMONAS, Stein. 



Animalcules irregularly pyriform, the anterior border obliquely truncate, 

 stationed singly at the extremities of an erect, rigid, perfectly hyaline and 

 homogeneous, variously branching pedicle or zoodendrium ; flagella two in 

 number, one long and the other short ; endoplast and one or more contrac- 

 tile vesicles usually conspicuous ; no distinct oral aperture, food-substances 

 being incepted at all parts of the periphery. Inhabiting fresh water. 



The rigid and erect composition and mode of growth of the pedicle in this genus 

 distinguish its representatives from those of Cladonema, The hyaline and homo- 

 geneous consistence of the pedicle, added to the solitary disposition of the zooids, 

 serves to separate it from Anthcphysa. 



