326 REPORT OF NATIONAL MUSEUM, 1897. 



SPIRILLINA VIVIPARA Ehrenberg. 



(Plate 71, fig. 4.) 



A circular, double concave disk, formed by a single tube closely 

 coiled in one plane; tube undivided, conspicuously perforated by a 

 single row of pores; sutures thick, but not raised; aperture, the open 

 end of the unconstricted tube. Diameter, 0.75 mm. {-./-.^ inch) or less. 



Localities. — Not recorded. 



SPIRILLINA LIMBATA Brady. 

 (Plate 71, fig. 5.) 



Circular, concave on both sides, composed of numerous regular coils 

 of a flattened tube; peripheral edge square; sutural line marked by a 

 raised ridge of shell substance: general surface smooth; perforations 

 very indistinct. Diameter, about 0.8 mm. (3^0 inch). 



Locality. — Not recorded. 



SPIRILLINA OBCONICA Brady. 



(Plate 71, fig. 6.) 



Circular, deeply concave on one side, moderately convex on the other ; 

 peripheral edge rounded; sutures deeply depressed on the concave face, 

 flush on the other; convolutions eight or ten; perforations on the con- 

 cave face only, at the summit of minute bead like prominences arranged 

 in a single row along the sutural side of the tube; tube slightly con- 

 stricted at regular intervals alternating with the perforations. Diam- 

 eter, 0.8 to 1.2 mm. (3V to aV inch). 



Locality. — Not recorded. 



Test spiral, rotaliform, rarely evolute, very rarely irregular or acer- 

 vuline. 



Genus CYMBALOPORA. 



Test more or less trochoid or complanate. Segments of the trochoid 

 forms spiral at the apex, subsequently arranged concentrically around 

 a deep umbilical vestibule with which each chamber communicates by 

 a neck. Complanate forms with rows of pores along the septal depres- 

 sions of the inferior surface. 



CYMBALOPORA POEYI d'Orbigny. 



(Plate 72, fig. 1.) 



Short conical, with rounded apex and flat base; composed of numer- 

 ous segments, at first arranged in a regular spiral, later in circles or 

 rings around a central vestibule, the segments of one auuulus alternat- 

 ing more or less regularly with the one above and below; segments 

 separated toward the center by irregular fissures ; surface conspicuously 



