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BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



Rarely they are triangular. The operculum of the ovicelled zooecia 

 is large, elliptical, transverse; the proximal sinus is very wide but 

 very little concave; the surface is finely wrinkled concentrically and 



C F 



A 



Fig. 147. — Genus Tremoschizodina Duvergier, 1922 



A-C. Tremoschizodina lata Smitt, 1873. A. Nonovicelled zooecia (After Smitt, 

 1873). B. Operculum of ordinary zooecium, X85. C. Operculum of ovicelled 

 zooecium, X85. 



D-F. Tremoschizodina crassa Canu and Bassler. Opercula of ordinary and 

 ovicelled zooecia, X85. 



bears two large transverse wrinkles. The muscular attachment is a 

 convex transverse line. 



Measurements . — 



Apertura [ha =0.12-0.15 mm. Apertura lha =0.20 mm. 



(ordinary) [la =0.15 mm. (ovicelled) [la =0.25-0.30 mm. 



Zooeciaf^= - 50 -°- 60mm - 

 [1st =0.35-0.50 mm. 



B C 



Fig. 147a. — Tremoschizodina crassa, new species 



A. A rare form of operculum and B, the usual type, X85. C. Operculum of 

 ovicelled zooecium, X85. 



Affinities. — This beautiful species resembles very much DaTcaria 

 torquata D'Orbigny but differs from it in its very characteristic aper- 

 ture bearing two triangular cardelles. 



The inconstancy of the avicularium is inexplicable, for it appears 

 to us too small for performing a zoarial function. 



In the interior the walls are thin and the zooecia rectangular; the 

 cardelles do not correspond to the interior condyles. 



Biology. — Almost all our specimens have been dredged living; they 

 were in reproduction in February, 1908 (18-37 meters). 



