iRT. 25 FORAMINIFERA CUSHMAN AND KELLETT 6 



open; chambers 12-15 in the last-formed coil, elongate, curved, the 

 apertural face convex; sutures distinct, depressed strongly at the 

 inner end, becoming less so toward the periphery, gently curved; wall 

 smooth, polished, very finely perforate; aperture elongate, at the base 

 of the apertural face, often slightly more extended on one side than 

 the other. 



Length, 0.50-0.63 mm.; breadth, 0.38-0.46 mm.; thickness, 0.22- 

 0.26 mm. 



Berry recently described this species from about 8 fathoms of water 

 at the mouth of the Tumbez River at Puerto Pizarro, Peru. We have 

 had specimens from Payta and Pimentel, Peru, which are evidently 

 this same species. The adult specimens have slightly more chambers 

 than does the type, but the measurements and proportions show that 

 there is a single species in the series. There is a tendency as noted 

 by Berry for the test to become slightly asymmetrical. 



Genus NONIONELLA Cushman, 1926 



NONIONELLA AURIS (d'Orbigny) 



Plate 1, figure 9; plate 2, figures 2. 3 



ValvuUna auris d'Orbigny, Voy. Am^r. M6rid., 1839, vol. 5, pt. 5, " Foramini- 

 feres," p. 47, pi. 2, figs. 15-17. 



Test asymmetrical, slightly trochoid, the spire not raised, periphery 

 in the adult broadly rounded; chambers 9-11 in the adult, low and 

 broad, very distinct, slightly inflated, in the adult with the last- 

 formed chamber having an enlarged portion extending over the 

 umbilicus on the ventral side; sutures distinct, depressed, gently 

 curved; w^all smooth, polished, very finely perforate; aperture at 

 the base of the last-formed chamber extending from the periphery 

 ventrally, low and broad. 



Maximum length, 0.40 mm.; breadth, 0.30 mm.; thickness, 0.18 

 mm. 



D'Orbigny described this species from many localities along the 

 west coast of South America from Chile to Ecuador saying that it 

 makes up nine-tenths of the foraminifera of the Peruvian coast. We 

 have found it in material from Payta, Pimentel, and Eten, Peru, and 

 from Corral and Lota, Chile. The bulbous expansion of the chamber 

 on the ventral side is often not taken on until the specimen is fully 

 developed and specimens in this state are figured. Farther north 

 and in the late Tertiary of Calfornia this is replaced by its probable 

 ancestral form, Nonionella miocenica Cushman which has fewer and 

 relatively larger chambers. 



It was suspected that Nonion pizarrensis Berry might be the 

 microspheric form of d'Orbigny 's species but apparently they are 

 distinct so far as the material we have will show. This relationship 

 is however suggested for future studies. 



