stokes.] 'J4:4 [Nov. 2, 



ing much in connection willi the surface plications or ridge-lil^e eleva- 

 tions, in early j'outli the raised lines being low, inconspicuous and 

 irregularly disposed ; in maturity becoming full; rounded and prominent, 

 separated by deep furrows, as if ilie wall of the lorica had become dis- 

 tended with liquid, dilatation taking place at expansile regions between 

 the ridge like markings of the earlierstage ; in the mature state thelateral 

 borders are protuberantly crenate. 



Acineta flexilis, sp. nov. (Fig. 16). — Lorica irregularly subspherical, 

 tapering posteriorly to the short, hollow pedicle ; anterior border 

 closed, thin, apparently perpendicularly lamelliform, the margin 

 irregularl}^ undulate ; two opposite lateral regions each bearing two 

 anteriorly approximating, posteriorly diverging, narrow fissures for the 

 passage of the tentacles, the fissures usually being open only sufficiently 

 for the passage of the tentacles, except daring the final development and 

 the escape of the embryo, when those on the lateral margins and that on 

 the frontal border are seen to be continuous, the expanding fissures clos- 

 ing after the escape of the embr3'o ; pedicle about one-seventh as long as 

 the lorica ; tentacles capitate, of two kinds and apparently issuing only 

 from the slit-like lateral fissures, one kind being straight, rigid, and not 

 often exceeding twice the length of the lorica, the other form filamentous, 

 flexible, writhing and variously curved and coiled, often extending to 

 more than five times the length of the lorica ; body of the animalcule sub- 

 spherical or obpyriforni, not filling the cavity of the lorica, and in no way 

 adherent to it ; endoplasm granular ; nucleus broadly ovate, located near 

 one lateral border ; contractile vesicle single, spherical, postero-lateral in 

 the region opposite the nucleus. Length of the lorica, including the 

 pedicle, ^\q inch. Eab. — Fresh water from near Trenton, N. J. ; attached 

 to Spirogyra. 



Codosiga florea Stokes (Journ. Trenton Nat. But. Soc, January, 1888, 

 Vol. i, No. 3). — This was incorrectly placed in the genus Codosiga; it is 

 a Monosiga, and should be referred to as Monosiga florea. 



Halsis furcata Stokes {Joiirn. Royal Micros. Soc, August, 1889). — 

 This generic name being preoccupied, it may, in this instance, be changed 

 to Halsiopsis, the single known species then being HaUiopsis furcata. 



Explanation of the Plate. 



Fig. 1. Salpingoeca globosa ; with collar retracted. 



" 2. SalpingcEca collaris. 



" 3. Prorocentrum hamatum. X 730. 



" 4. Trachelomonas fusiformis. X 500. 



" 5. Trachelomonas sphterica. X 400. 



" 6. Trachelomonas acanthophora. X 500. 



" 7, 8. Vaginicola longipes. X 200. 



" 9. Caulicola valvata. X 400. 



' ' 10. Bicosceca phiala ; empty lorica, X 835. 



