228 



THE AMERICAN MONTHLY 



[December, 



developed ligament ; contractile vesi- 

 cles, two. Length of lorica 2 g'o',)" irich ; 



r 

 / 



Fig. 27. — New Fresh-Water Infusoria. 



w^idth of the anterior aperture ^xrW 

 inch. Habitat, — Pond water; on 

 filamentous algse or other fine vege- 

 table fibres. Solitary or scattered. 



Five individuals of this easily rec- 

 ognizable species have been observed 

 attached at almost equidistant points 

 to a vegetal fibre. These constitute the 

 entire number thus far noticed, and 

 even these few seem somewhat vari- 

 able in two characters. With two in- 

 dividuals the enclosed zooid was con- 

 nected with the lorica by a posteriorly 

 developed ligament ; in one the lorica 

 was at its hindmost border so suddenly 

 tapered that the'pedicle seemed a deli- 

 cate solid stem, while in the remain- 

 ing four the lorica was apparently 

 continued for about one-half the en- 

 tire length of the stem by means of a 

 hollow^ gradually -narrowing foot- 

 stalk. As this was the prevailing con- 

 dition in the few observed, it is shown 

 in ficf. 3. 



Desmarella irregularis^ sp. nov. 

 Fig. 3 ; diagram. 



Bodies ovate, constricted beneath . 

 the insertion of the membranous 

 collar, somewhat gibbous, scarcely 

 changeable in shape ; laterally united 

 into irregular colonies formed of as 

 many as fifty individual zooids, the 

 external or superior surface usually 

 being unevenly convex and the pe- 

 riphery more or less circular, the 

 clusters frequently separating into 

 smaller companies and remaining 

 temporarily attached through the in- 

 termedium of one or more extremely 

 fine filaments ; flagellum five or six 

 times as long as the body ; contrac- 

 tile vesicles, two, opposite, near the 

 centre of the lateral borders ; nucleus 

 single, spherical, subcentrally situ- 

 ated ; endoplasm granular. Length 

 of body ^gJ^-Q to -g^VTr inch. Habi- 

 tat. — Fond water. Movements not 

 rapid. 



This previously undescribed form, 

 the first member of the genus thus far 

 obtained from American waters, is re- 

 markable for several characteristics. 

 Its compound colonies are noteworthy 

 in respect to the number of individual 

 animalcules composing them, as many 

 as fifty having been observed in a sin- 

 gle irregularly extended and some- 

 what convex cluster. The individual 

 zooids are united either by the direct 

 contact of their lateral borders at a 

 single point of contact, or through 

 the intermedium of a very short ex- 

 tension on each side of the body. It 

 is probably this usually inconspicuous 

 portion which is drawn out into the 

 fine thread-like extension of the sar- 

 code when the original colony-stock 

 separates in two parts, the filaments 

 eventually breaking and the clusters 

 then floating independently of each 

 other. These partially separated por- 

 tions increase the irregular appear- 

 ance so noticeable in most of the colo- 

 nies. The flagellum of each zooid is 

 of extraordinary length, and often dis- 

 tally bulbous. 



I. Mono siga Hmnobia, 



Explanation of Fig. 27. 

 2. Saipingxca eurystoma. 3. C\\ister oi Desmarella irregularis. 



