THE AMERICAN MONTHLY 



[January, 



ment held for a long time — so long as 

 the prisms were in use. — Ed.] 



New Members of the Infusorial 

 Order Choano-Flagellata, S. K. 

 —III. 



BY ALFRED C. STOKES, M. D. 



In continuation of this subject, 

 which has become a very attractive 

 one to me, and on which I have pre- 

 viously ventured to offer two papers 

 to the readers of this Journal, I now 

 present the following notices of pre- 

 sumably undescribed forms of these 

 minute but most beautiful infusoria, 

 in this instance chiefly collected from 

 small ponds in Western New York : 



Monosiga obovata^ sp. nov. 



Body smooth, transparent, clavate 

 or obovate, three and one-half to four 

 times as long as bi'oad, widest ante- 

 riorly, constricted at the line of inser- 

 tion of the collar, and attached by the 

 attenuate posterior extremity to the 



summit of a rigid, comparatively 

 thick foot-stalk about three times the 

 zooid in length ; collar narrow ; nu- 

 cleus and contractile vesicle conspicu- 

 ous ; length of the body, 0.0009 ii^ch. 



Habitat. — Attached to the rootlets of 

 Lemna in shallow ponds in Western 

 New York. 



The body bears a remote resem- 

 blance to that of Monosiga augus- 

 tata^ S. K. The creature conspicu- 

 ously differs, however, in being ele- 

 vated on the long pedicel, in being 

 broader anteriorly, and in possessing 

 a less attenuate posterior extremity. 

 Its size is also very much greater. It 

 is represented in Fig. i , magnified 950 

 diameters. 



Codosiga utriculus, sp. nov. 

 Bodies elongate-obovate, widest in 

 front of the transverse axis, slightly 

 constricted at the point of insertion 

 of the collar, three and one-half to 

 four times as long as wide, attached 

 by attenuate posterior extremities in 

 clusters of four to the summit of a 

 straight, rigid foot-stalk four to five 

 times as long as the zooids, the pedicel 

 occasionally becoming colored chest- 

 nut-brown after maturity ; length of 

 body, y^5o inch. Habitat. — On 

 Lemna rootlets in ponds in West- 

 ern New York. 



Several colonies of this species 

 have been met with, among them 

 a single one whose pedicel had as- 

 sumed, presumably with age, a 

 chestnut-brown color. So far as 

 I am aware there is no record of 

 such color change in connection 

 with the pedicel of any member 

 of the order, and when first ob- 

 served with this species of Codo- 

 siga I thought it might possibly 

 be restricted to it, since W. Sa- 

 ville Kent, who has made a special 

 study of the order from English 

 waters, has not recognized the 

 change in any of the numerous 

 forms which he has discovered. 

 But it happens that one of the most 

 beautiful and attractive species, 

 Codosiga umbellata (Tatem) S. 

 with a compound pedicel resem- 

 bling, as the specific name indicates, 

 the clustered flower-stalks of the Um- 

 belliferte, at times presents the same 

 peculiarity. Several colonies have 

 been observed in this condition. In- 



K 



