394 



BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



Hippodiplosia (Lepralia) asperrima Reuss, 1847. Tortonian. 

 Hippodiplosia (Lepralia) aperta Manzoni, 1874. Tortonian. 

 Hippodiplosia (Lepralia) megalota Reuss, 1847. Tortonian. 

 Hippodiplosia. (Eschara) ampla Reuss, 1847. Tortonian. 

 Hippodiplosia (Eschara) biauriculata Reuss, 1847. Tortonian. 

 Hippodiplosia (Eschara) oculata Manzoni. 1871. Tortonian. 

 Hippodiplosia granulosa Canu, 1915. Aquitanian. 

 Hippodiplosia verrucosa. Canu, 1915. Aquitanian. 



HIPPODIPLOSIA VESPERTILIO, new species. 



Plate 52, figs. 5-12. 



Description. The zoarium is free, formed of two lamellae fused together and 

 inseparable; the fronds are narrow and bear 4 to 6 longitudinal rows of zooecia. 



The zooecia are long, 

 distinct, sinuous, clavi- 

 forin; the frontal is 

 convex; it is a thick 

 tremocyst with tu- 

 bules resting on a 

 very thin, perforated 

 olocyst. The aper- 

 ture is elliptical, elon- 

 gated, provided with 

 two very small, in- 

 constant cardelles. 

 The ovicell is globu- 

 lar, little salient, little 

 FIG. 117. Genus Hiinioiiiinosia (_anu, 1916. , ,, , . , ,. 



imbedded in the distal 

 A-F. Hippodiplosia pallasiana Moll, 1803. A. Ordinary zooecia, X 30. . , , , , 



B. Ovicelled zooecia, X 20. (A, B after Hincks, 1880.) C. Young la, C 



zooecium, X 40. D. Multiporous septula. E. Distal wall, X 20. F. operculum when it, 

 Lateral wall, X 20. (C-F after Levinsen, 1894.) opens; it is surround- 



ed by areolae. Two 

 tubular symmetrical avicularia open on each side of the aperture. 



Measurements. 



2Mb.,. ._ 



Aperture , ., , 



I, I fa=0.11 mm. 



Zooecia 



Lz= 0.60-0.75 mm. 

 mm. 



Variations, In the interior (fig. 9) the aperture is oblique; the tubules are 

 visible by transparency through the very thin olocyst. The longitudinal section 

 (fig. 7) shows zooecial alternation due to the closeness of the border of the zoarium ; 

 there is a large distal septula and we are able to verify five or six lateral septulae. 

 The longitudinal section (fig. 10) indicates that the operculum ought to close the 

 ovicell in opening, although we cannot be rigorously certain of this. It is evident 

 rhat if the ovicell was closed by a special membrane, it would be necessary to create 



