AET. 6 FORAMINIFERA: POLYMORPHINIDAE — CUSHMAN AND OZAWA 139 



Dimorphina millettii, described by Sidebottom from off the east 

 coast of Australia, 465 fathoms, having an elongated quadrangular 

 test with a sigmoid arrangement of the chambers, is very similar to 

 S. williamsoni. The difference is only an extra chamber which is 

 added on the top of the main test. Such specimens, having a 

 round extra chamber, are often found in shallow water off England 

 and Belgium. 



Distribution. — S. williamsoni appears to be rather common in the 

 shallow water off England and Belgium, from where we have num- 

 erous specimens. Some forms very similar to the present species are 

 reported from off east Australia. We also have a few fossil specimens 

 which are something like the present species, but not enough material 

 to be positive of the identification. 



SIGMOMORPHINA CONCAVA (Williamson) 



I Plate 38, figures 5-7 



Polymorphina lactea Walker and Jacob var. concava Williamson, Recent 

 Foram. Great Britain, 1858, p. 72, pi. 6, figs. 151, 152, 



Excepting the last attached part, the test is oval and much com- 

 pressed; chambers elongate, much embracing unequally on either 

 side, each succeeding chamber extending down to the base, attached 

 part (or chamber ?) generally highly convex, leaving a large space 

 between the test and the foreign object, but without visible aperture; 

 sutures not depressed, distinct; wall smooth, rather thin and almost 

 transparent; aperture radiate. 



Williamson was the first who noticed an unmistakably parasitic 

 species of the Polymorphinidae which he named Polymorphina concava. 

 We have several attached specimens, some of which are the same as 

 that figured by Williamson. The present species is undoubtedly a 

 specialized one among the Polymorphinidae. No other species having 

 a test resembling that of Sigmomorphina concava is known, therefore 

 Williamson's species is taken as a valid one. 



Distribution. — Sigmomorphina concava seems to be extremely rare. 

 Williamson gives Brixham, England, as the locality whence his 

 specimens were obtained. We have specimens from off the Belgian 

 coast, from the Mediterranean, and off the island of Delos, 10-14 

 fathoms. We have also a specimen here figured from the Pliocene of 

 Monte Mario, near Rome. 



SIGMOMORPHINA ALICEAE Cashman and 02iawa, new species 



Plate 38, figures S a, b 



Test oblong, compressed, twisted nearly 180°, greatest width in 

 upper half, tapering toward the initial end; chambers elongated, 

 especially the early ones, later ones becoming broader, compressed, 

 not much embracing, arranged in a contraclockwise sigmoid series, 



