82 



THE AMERICAN MONTHLY 



[May, 



and somewhat gibbous, about twice 

 as long as broad, widest centrally, 

 obtusely pointed posteriorly, the en- 

 tire svn-face more or less covered, 

 often almost concealed, by adherent, 

 irregular and angular sand grains ; 

 anterior extremity constricted to 

 form a short neck-like prolongation, 

 the circular border thickened, ex- 

 panded, and obliquely truncate; 

 flagellum large, equalling or exceed- 

 ing the body in length ; nucleus not 

 observed; contractile vesicle (?) 

 single, laterally placed near the an- 

 terior extremity ; pharynx apparently 

 extending to near the body-centre. 

 Length of body, ^^.^y inch. Habi- 

 tat. — Fresh water with Alga^. 



The movements of this remarkable 

 infusorian are usually rather rapid, 

 resembling those of Urccolus cyc/os- 

 /(9;;/a (vStein) Mercsh. {PJiialoncnia 

 cvclostoma Stein), the obliquely 

 truncate anterior extremity being ap- 

 plied to the submerged surface, and 

 the body lifted at an acute angle, the 

 vibrating tip of the Hagellum ap- 

 pearing to be the only means by 

 which an advance is made. The 

 oral region and the entire body are 

 verv soft and elastic, but scarcely 

 changeable in shajje. The food par- 

 ticles and frequently small aggrega- 

 tions of minute fragments are drawn 

 into the oral aperture with some 

 force, often being quite violently 

 dragged away from their attachment. 

 The phar-\ngeal passage and nucleus 

 were obscured by the abundance of 

 the cuticular coating of sand grains ; 

 the former, however, appeared to 

 reach the centre of the body. 



The cuticular investment of sand 

 grains which is almost unique among 

 the fresh-water Infusoria, seems to 

 be entirely under the creature's con- 

 trol, so far as the amovint and ar- 

 rangement of the constituent parti- 

 cles are concerned. The process of 

 obtaining these grains is, so far as I 

 have observed, simply one of adhe- 

 sion. The infusorian passes above a 

 coveted particle and it adheres to the 

 presumably viscid surface. This is, 



at least, the process which takes 

 place on the stage of the microscope, 

 the silicious and other fragments ad- 

 hering wherever they come in contact 

 with the body surface. Their subse- 

 quent arrangement into the semblance 

 of a protective sheath I have not been 

 able to satisfactorily observe. It 

 seems, however, to be accomplished 

 by a slow movement or superficial 

 and deliberate circulation of the ecto- 

 plasm, by means of which the grains 

 are gradually moved into their places 

 according to their size and shape. 



For several years I have frequently 

 met with small, ovate, actively-mov- 

 ing, uniflagellate organisms, the en- 

 tire surface being more or less abun- 

 dantly clothed with minute sand 

 grains ; and now that this remark- 

 ably interesting infusorian has been 

 observed, to associate these little uni- 

 flagellate sand -bearers with it is an 

 irresistible impulse ; but, although 

 the supposition of their intimate 

 connection is plausilile, it has no 

 other than an imaginary basis. The 

 particular organism from which 

 figure 7 was made was yijVo '^^'^^^ 

 in length, and its load of sand was 

 unusually large. Similar but very 

 much smaller forms have been re- 

 peatedly observed from widely-sepa- 

 rated localities. These very small 

 uniflagellate bodies, however, are 

 generally the bearers of very few 

 sand particles, which are often ag- 

 gregated at the rounded summit or 

 on one lateral border. I now sus- 

 pect an intimate connection between 

 these little creatures and the mature: 

 Urceolus sabulosus. If they are 

 not immature or developing forms, 

 of Urceolus, then they must be a 

 unique species of Monas. 



Ch rysop vx i s triangularis^ sp. 

 nov. (Fig- 8.) 



Lorica triangular, sessile, com- 

 pressed, the height slightly exceed- 

 ing the breadth, the posterior ex- 

 tremity truncate, the basal angles 

 rounded ; lateral margins converg- 

 ing, with a more or less conspicu- 

 ous sub - central convex projection ; 



