THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL 



Vol. Y. 



Washington, D. C, July, 1884. 



No. 7. 



Notices of New Fresh-water Infu- 

 soria. 



BY DR. A. C. STOKES. 



Hymenostotna ., gen. nov. (Greek, 

 hymen ^ a membrane; stoma ^ a 

 mouth). 



Animalcules free-swimming, ovate, 

 more or less depressed, entirely cili- 

 ate, a fascicle of several diverse, flex- 

 ible setose cilia projecting posteriorly ; 

 adoral groove large, ventrally dis- 

 posed, somewhat on the right-hand 

 side of the median line, bearing on 

 its left-hand margin a row of vibra- 

 tile cilia, and on its right-hand border 

 a voluntarily vibratile membrane ; 

 oral aperture ovate, situated at the 

 posterior and deepest part of the 

 adoral depression, and bearing an ex- 

 tensile and retractile membrane on 

 its anterior and left-hand margins ; 

 contractile vesicle double ; nucleus 

 posteriorly located ; anal aperture 

 postero-terminal. 



Hyinenostoma hymenophora^ n. 

 sp. 



Body ovate, depressed, persistent 

 in form, the length about twice the 

 width, striate longitudinally and en- 

 tirely ciliate ; dorsal surface convex, 

 the ventral flattened, somewhat con- 

 cave ; the posterior extremity round- 

 ed, the anterior slightly emarginate ; 

 the left-hand border convex, the right- 

 hand margin somewhat flattened ; 

 cilia of the cuticular surface fine 

 and short, those on the posterior ex- 

 tremity more conspicuous, the pos- 

 teriorly projecting, setose fascicle 

 formed of hair-like, flexible cilia of 

 diverse length, two being usually of 

 equal length and distally curved, the 

 whole commonly directed obliquely 



toward the left ; adoral depression 

 large, obovate, longitudinally dis- 

 posed, widest anteriorly and extend- 

 ing backwards and inwards for a dis- 

 tance equalling about six-sevenths of 

 the entire length of the body ; oral 

 aperture large, ovate, placed on the 

 right-hand side of the median line of 

 the adoral depression, the extensile 

 and retractile membrane which partly 

 surrounds it thrown into folds on its 

 left-hand margin ; adoral cilia fine, 

 dense, extending across the adoral 

 depression and oixlinarily visible oidy 

 after the infusorian's death ; the mem- 

 brane attached to the right-hand bor- 

 der of the adoral groove voluntarily 

 vibratile, projecting from the anterior 

 extremity as a short, conical, hood- 

 like extension, one side of this pro- 

 jection inserted on the anterior left- 

 hand margin of the adoral depression, 

 the other side continued as a conspic- 

 uous, lamellate membrane for about 

 one half the length of the adoral 

 groove, when it is abruptly narrowed 

 and thence descends into the depres- 

 sion, is continued to its posterior ex- 

 tremity and apparently extended to 

 surround the oral aperture ; nucleus 

 elongate, band-like, cuned, posteri- 

 orly located near the right-hand bor- 

 der ; contractile vesicle double, di- 

 verse in size, one very small and sit- 

 uated near the dorsal surface and 

 sub-central to the right-hand margin, 

 pulsating quickly and almost.imme- 

 diately reappearing through the co- 

 alescence of several minute vacuoles ; 

 the other large, posteriorly placed 

 somewhat to the left-hand side of the 

 median line, pidsating at long inter- 

 vals and forming slowly ; paren- 

 chyma transparent, minutely granu- 



