GENUS HYMENOMONAS. 



407 



Chlorangium stentorinum, Ehr. sp. Woodcut, Figs. 1-7. 



Bodies elongate-ovate or subfusiform, about three times as long as 

 broad ; flagella terminal, subequal, not so long as the body ; endoplasmic 

 colour-bands bright green, produced throughout the whole extent of the 

 two lateral borders, one of these including near its distal end an obscure 

 eye-like pigment-spot ; contractile vesicle situated at the anterior ex- 

 tremity, close to the insertion of the flagella ; endoplast spherical, sub- 

 central, attached during the sedentary condition to a short, simple, or 

 slightly branching pedicle, in groups of from two or three to ten or twelve 

 zooids. Length of zooids 1-1150". 



Hab. — Pond water, on various Entomostraca. 



Chlorangium stentoriKum, Ehr. sp. — r. Free-swimming biflagellate zooid ; c v, contractile vesicle ; e, eye-Iilce 

 pigment-spot ; «, nucleus or endoplast. 2. Encysted zooid attached by a slalk-like prolongation of its anterior extre- 

 mity. 3 and 4. Encysted zooids, with body-substance separated respectively into two and four segment-masses. 

 5. Further developed stage of the preceding example, in which the four segment masses having burst the cyst wall, 

 remain attached distally to the parent pedicle ; at «, residual portion of the primary cyst. 6. Adult sedentary colony- 

 stock, produced through the further subdivision of the zooids represented in the preceding figure. 7. Single encysted 

 zooid, whose body-mass has become subdivided into minute sporular elements. (After Stein, X 480.) 



This species was first described by Ehrenberg under the title of Stentor {l)pygm<zus, 

 but is relegated in his subsequent work, ' Die Infusionsthierchen,' to the genus 

 Colacium, The grounds upon which it has been found necessary to separate it 

 from this last-named generic group, have been already indicated. The growth of 

 the sedentary arborescent colony-stocks of this animalcule are produced, according 

 to Stein's recently pubUshed volume, and as shown in the accompanying woodcut, 

 by the endogenous subdivision of a primary attached zooid, whose cuticle finally 

 bursting exposes the internally developed units, each with its anterior extremity 

 firmly attached to the extremity of the parent pedicle. A portion of the posterior 

 region of the parent cuticle frequently remains for a considerable interval embracing 

 the base of the common stock and presenting, as seen in profile, Fig. 5^', the aspect 

 of two lateral setose processes. Sporular multiplication, in which encysted zooids 

 attached singly to their pedicles become divided up into a number of minute micro- 

 spores, as shown at Fig. 7, is also placed on record by the authority just quoted. 

 A distinct oral aperture has apparently as yet not been detected, but probably 

 exists and corresponds with that possessed by Colacium. 



Genus IX. HYMENOMONAS, Stein. 



Animalcules solitary, free-swimming, secreting a more or less flexible 

 lorica ; flagella two in number, subequal ; lateral pigment-bands con- 

 spicuously developed ; no eye-like speck ; contractile vesicles anteriorly 

 located. Inhabiting fresh water. 



