GENUS CHILOMONAS. 423 



dorsal one convex ; endoplasm very clear and transparent, enclosing 

 nodular corpuscles of irregular shape and size, many of these located on 

 or close to the surface, and imparting to it a tuberculate aspect ; flagella 

 subequal, the anterior slightly the longer, exceeding the body in length ', 

 endoplast spherical, subcentral ; contractile vesicle posteriorly situated. 

 Length of body 1-250x3". 



HAB. Vegetable infusions in both salt and fresh water. 



This form was obtained by the author in equal abundance in the hay infusions in 

 both salt and fresh water productive of the preceding type. It is worthy of remark, 

 however, that while in the salt-water infusion this species preceded D. vorax by a 

 few days in its advent, the reverse happened in the case of the fresh-water one. 

 Although in their predacious habits, and in the manner of chasing and incepting 

 their food, the two species closely correspond with each other, their external appear- 

 ances are altogether diverse. The smooth, persistent, subpyriform shape of the variety 

 last described is here replaced by a contour which, while more frequently irregularly 

 ovate, with a slightly pointed posterior extremity, as represented at PI. XXIV. 

 Figs. 44 and 45, may in other instances be produced at this region into a long 

 tail-like process, as shown at Fig. 43, which communicates to it a singular rat-like 

 contour. On the other hand, it not unfrequently assumes an almost perfectly 

 spheroidal shape. The habits of this species appear to be slightly more omni- 

 vorous than those of Dinomonas vorax, for in addition to its ordinary diet of smaller 

 monads, which are seized and swallowed in a manner similar to that already 

 related of the last-named type, long bacillar-like filaments, as shown at Fig. 45, are 

 not unfrequently ingested. Multiplication by longitudinal fission was observed on 

 several occasions, as likewise the formation of spherical encystments. 



Fam. VII. CHILOMONADID-ffi, S. K. 



Animalcules free-swimming or temporarily adherent, illoricate ; oral 

 aperture conspicuously developed, communicating to the anterior border a 

 bilabiate or excavate appearance ; flagella two in number, both vibratile or 

 undulating in the natatory state, but one of them coiled upon itself when 

 the zooid is at rest, adherent through a greater or less portion of its length, 

 and used for the purpose of temporarily anchoring it to submerged objects ; 

 endoplasm transparent, granular ; no eye-like pigment-spot. Inhabiting 

 salt and fresh water. 



The most important distinction of this family group as here defined, is afforded 

 by the anchoring faculty possessed by one of the two flagella, this feature to 

 some extent approximating it toward the Anisonemidae next described. In none 

 of the representatives of this last-named group, however, does the anchoring 

 flagellum exhibit that characteristic coiled contour so conspicuous in the present 

 instance. Furthermore, the anchoring flagellum in Chilomonas and its allies is 

 vibratile and subservient to the purpose of locomotion, in place of being trailed 

 motionlessly in the rear, as obtains among the succeeding group. A modification of 

 the flagella, in which loop-like coils for the purpose of attachment are developed at 

 the base of each appendage, has been already recorded in connection with the genus 

 Polytoma. 



GENUS I. CHILOMONAS, Ehrenberg. 



Animalcules free-swimming, ovate or elongate, not metabolic but plastic 

 and subject to considerable alteration in form, the anterior extremity 

 obliquely truncate, projecting superiorly, and presenting the aspect of a 



