226 



THE AMERICAN MONTHLY 



[December, 



kills the organisms that mav be pres- 

 ent, but also the spores which, in some 

 cases, are not killed bv boiling. For 

 this reason we -have been led to ex- 

 periment with baked potatoes, as it 

 is probable that no spores can with- 

 stand the temperature of an oven 

 when potatoes are baked. The result 

 has been eminently satisfactory so far 

 as cultures of J/! luteus are concerned. 

 The potato may be baked, placed un- 

 der a bell-jar which has been heated 

 in the oven until thoroughly steril- 

 ized, and there is not much danger of 

 contamination. 



Notices of New Fresli- Water In- 

 fusoria. — II. 



BY ALFRED C. STOKES, M. D. 



Opercularia plicatilis^ sp. nov. 

 Body elongate-ovate or somewhat 

 conical-vase-shaped, smooth, soft and 

 flexible, the length two and one-half 

 to three times the width ; when ex- 

 tended constricted beneath the peris- 

 tome border, widest in front of the 

 middle, tapering and attenuate poste- 

 riorly; when contracted broadly ovate- 

 . pyriform or subspherical. thrown into 

 transverse folds posteriorly and bear- 

 ing anteriorly a snout-like, crenulated 

 and longitudinally plicate projection ; 

 parenchyma of the body and ciliary 

 disc enclosing numerous green coi"- 

 puscles, that of the peristome border 

 and posterior one-third of the body 

 usually coloidess and finely granular, 

 the cuticular surface of the latter part 

 finely striate lengthwise ; peristome 

 border as wide as the body, some- 

 what everted, the mai'gin crenulate ; 

 ciliary disc considerably and obliquely 

 elevated ; ciliary circles two ; mem- 

 brandus collar large and conspicuous ; 

 pedicle rigid, finely striate longitudi- 

 nally, dichotomous, or umbellate with 

 three or more branches, and gradually 

 increasing in thickness from the point 

 .of attachment to that of division ; 

 zooids attached in subsessile clusters 

 of from ten to twenty members; nu- 

 cleusband shaped, curved, transverse- 

 ly placed anteriorly; contractile vesicle 



single. Length of extended body -^\^ 

 inch ; height of entire colony ^ to 

 Jy-inch. Habitat. — Pond water ; at- 

 tached to Ceratop/iylli//)! and Ana- 

 charis. 



These colonies are comparatively 

 so immense in size that they are ap- 

 parent to the unaided vision. They 

 occur in some profusion on the leaf- 

 lets of various aquatic plants, the 

 zooids there forming subspherical 

 clusters about -^-^ inch in diameter. 

 The foot-stalk, stout, erect and rigid, 

 presents two distinct methods of di- 

 vision : simple furcation into two ap- 

 proximate brandies as in figure i, 

 and a trifid or quadrifid umbellate 

 formation with the branches bifur- 

 cated or not, as in the diagram (Fig. 

 2.) Which form shall be selected 

 seems to depend upon the vital ac- 

 tivity, and consequently the uncom- 

 fortably crow'ded condition, of the 

 zooids. 



In the contracted phase the poste- 

 rior transverse annulations closelv re- 

 'Sen^ble those characteristic of Epis- 

 tylis plicatllis Ehr, when in the 

 same state, and suggested the specific 

 name. Thev, in connection with the 

 anterior snout-like projection, with 

 the distinct marginal crenulations and 

 the conspicuous longitudinal plica- 

 tions, readily distinguish the species 

 from all other members of the genus. 

 In Fig. I is shown a small colony 

 w'ith the most usual form of foot- 

 stalk ; in Fig. 2 the comparatively 

 rare umbel-like division, while Fig. 

 3 exhibits a contracted zooid and 

 Fig. 4 the characteristic parts of an 

 extended individual. The quadrifid 

 division of the foot-stalk seems very 

 uncommon. 

 !' A method of multiplication for the 

 ; dissemination of tlie species is by the 

 subdivision of the body into several 

 subglobose or pyriform parts,' each 

 bearing a subcentrally located ciliary 

 girdle. At times one, of these mi- 

 grant zooids -attaches itself to the 

 ; primary foot-stalk' of the colony and 

 I secretes a long nan'ow indi^•idual 

 ' pedicle, thus complicating the animal- 



