38 BULLETIN 9C, UNITED STATES NATIONAL MUSEUM. 



GASTROPELLA VENTRICOSA, new species, 

 riate 4, fig. 3. 



Description. — The zoariiim is free, cylindrical, bifurcated. The 



zocecia are large, elliptical, swollen; the frontal is smooth, conA^ex, 



garnished laterally with some large areolae. The ascopore is very 



large, not salient, placed in the upper third of the zocecia. The 



peristome is salient and sharp; the peristomice is oblique, orbicular 



or elliptical. The ovicell is entirely hidden within the thickness of 



the frontal of the distal zocecium. 



. . [A »e= 0.10-0.15 mm. 



Measurements. — Feristomice , ^.^f, 



[Ipe =0.15 mm. 



Zs=0.85 mm. 



Zocecia ^ , ^ , ^ 



\lz =0.40 mm 



Affinities. — There is frequently a very small peristomial avicu- 

 larium. On the longitudinal sections the ascopore manifestly opens 

 below the apertura and it often appears like a large funnel. On the 

 ovicelled zocecia there is a sort of clamp which is perhaps intended 

 to fasten the operculum during the expulsion of the larva. 



Occurrence. — Midwayan: Mabelvale near Little Eock, Arkansas 

 (common). 



Type.—Q^i. No. 62589, U.S.N.M. 



Family HIPPOTHOIDAE Levinsen, 1909. 



The zocecia become calcified from behind in successive zones for- 

 ward, leaving at the surface more or less salient lines, the lines of 

 growth, and are furnished Avith a variable number of dietellae. 



The genera of this family are as follows, those represented in 

 American deposits being marked with an asterisk. 



* Eippothoa Lamouroux, 1821. Lutecian-Eecent. 

 Chorizopora Hincks, 1880. Eecent. 



* Trypostega Levinsen, 1909. Jacksonian-Eecent. 

 Haplopoma Levinsen, 1909. Tortonian-Eecent. 

 Dacryopora Lang, 1914. Cenomanian-Senonian. 



Family ESCHAEELLIDAE Levison, 1909. 



The ovicell is hyperstomial. The operculum is rigid and chiti- 

 nous ; it closes the aperture, the compensatrix, and often the ovicell ; 

 its form is in rapport with the hydrostatic system, and the passage 

 of the eggs into the ovicell. 



This family is the reunion of the old families of Microporellidae, 

 Myriozoidae, and Escharidae (part) of Smitt and Hincks. Levin- 



