46 



PROCEEDINGS OP THE NATIONAL MUSEUM 



TOL. 72 



elongated, claviform; the frontal is much calcified, granulated, convex, 

 perforated at the middle by a small pore (pseudoascopore). The 

 aperture is suborbicular, somewhat elongated or a little transverse; 

 the proximal border is concave; there are two salient cardelles at the 

 bottom of the peristomie. The ovicell is hyperstomial, much imbed- 

 ded in the distal zooecium, large, globular, formed of two calcareous 

 superposed lamellae, the exterior of which is also much granulated; 

 the orifice is large and closed by the operculum. The avicularia are 

 large, triangular, much elongated, with a very thin beak and two 

 lateral denticles. 



Fig. 6.— Genus Tremogasteeina Canu, 1911, A. Teemoqasteeina lanceolata 



NEW SPECIES. OPEECULAR VALVE, X 85. B-F. TREMOGASTEEINA GEANULATA, 

 NEW SPECIES. B. OEDINAEY OPERCULUM, X 85. C. OPERCULUM WITH THICK 

 CHITINOUS BAND. D. ANOTHER FOEM OF OPERCULUM, X 85. E. MANDIBLE, X 

 85. F. LONGITUDINAL SECTION THEOUGH AN OVICELLED SPECIMEN, X 20. THE 

 ZOOECIAL WALL IS MUCH CALCIFIED. THE OVICELL IS HYPEESTOMIAL, CLOSED BY 

 THE OPEECULUM 



,, ^ A J. f^a = 0.20 mm. 



Measurements. — Aperture^, 



^ lZa = 0.20 mm. 



„ . jLz = 0.7 5 mm. 

 Z/ooeciai, _ „_ 



[lz = 0.35 mm. 



. . , . fiat; = 0.50 mm. 

 Avicularia 7 ^ on 



[lav = 0.20 mm. 



Structure. — The opercular valve is much chitinized; it is orna- 

 mented with a continuous sclerite distant from the border; it easily 

 separates from the ectocyst but it is attached to it. It is therefore 

 almost analagous to the operculum of Petralia. 



Each zooecium is adjacent to two avicularia. The frontal of the 

 latter is very diflQcult to understand. 



On the interior the two cardelles are salient; the frontal is smooth 

 and perforated by the two reniform pores or by three pores arranged 

 in a triangle; the avicularia are not visible, and in spite of their 

 exterior aspect they are clearly adventitious and probably have a 

 zooecial function. 



