132 BULLETIN 125, UNITED STATES NATIONAL MUSEUM. 



Genus HIPPOMENELLA Canu and Bassler, 1917. 



(For description see Bulletin lOG, U. S. National Museum, p. 379.) 

 mPPOMENELLA INFKATELUM Canu and Bassler, 1919. 



Plate 6, fig. 2. 



1919. Hippomenella infratclam Canu and Bassler, Geology and Paleontology of the West Indies 

 Bryozoa, Publications of the Carnegie Institution of Washington, Ko. 291, p. 92, pi. 6, fig. 2. 



Description. — The zoarium is a narrow Eschara borne on an expanded base. 



The zooecia are elongate, distinct, elliptical; the frontal is convex, surrounded by a 



line of small areolar pores and formed of a pleurocyst very finely granulated. The 



apertura is elliptical, elongate, with two very small cardelles. The avicularium is 



salient, elliptical with pivot, placed on the line of pores in the lower part of the 



zooecium. 



,, .Ax (/wi =0.16-0.20 mm. ^ . fiz =0.60-0.70 mm. 



Measurements. — Apertura , „ ,, Zooecia ^ „ ,„ „ r,^ 



^ I Za =0.14 mm. | Zs =0.40-0.50 mm. 



Affinities. — The only specimen found has been figured. The species is abso- 

 lutely characterized by its elliptical avicularium placed inferiorly, a character which 

 does not exist in the other species of the genus. We have observed a rather rare 

 case of regeneration of a zooecium by an avicularium (sr) . 



Occurrence. — Lower Miocene (Bowden marl) : Cercado de Mao, Santo Domingo 

 (very rare) . 



Holoti/pe.— Cat. No. 68610, U.S.N.M. 



Genus HIPPOPORELLA Canu and Bassler, 1920. 



(For description see Bulletin 106, U. S. National Museum, p. 377.) 



HIPPOPORELLA SPINOSA. new species. 



Plate 19, fig. 10. 



Description. — The zoarium incrusts other bryozoa. The zooecia are distinct, 

 separated by a deep furrow, somewhat elongate, elliptical; the frontal is smooth, 

 very convex, garnished laterally with small areolar widely spaced pores. The 

 apertm-a is elongate, the proximal border is almost straight; the two small cardelles 

 are placed very low; the peristome is little salient and bears six spines. There is a 

 vestibular arch. The ovicell is large, globular, salient, never closed by the 

 operculum. 



Measurements.-Apevtuvat ='^.]l ™^- Zooecial^ =^-^0 mm. 



I la =0.10-0.12 mm. [ Iz =0.35 mm. 



Variations. — The zooecia are rather variable in aspect and measurements; 

 however, the number of spines, the vestibular arch, and the place of the cardelles 

 are very constant characters which permit no confusion with the species which we 

 have described from the American Eocene. 



Occurreftce.— Miocene (Yorktown) : Yorktown, Virginia (rare). 



Ilolotype.— Cut. No. 68611, U.S.N.M. 



