80 PATAGONIAN EXPEDITIONS : PALAEONTOLOGY. 



excavated in the middle. Ventral (larger) valve more convex than the 

 dorsal, obtusely carinated. 



Measurements: (according to v. Ihering) Length, 19 mm. 



Width, 15 mm. 



Remarks: All our individuals are smaller than v. Ihering's and less 

 elongated, which is apparently due to the younger age : the lines of growth 

 in v. Ihering's figure indicate that the younger shell was comparatively 

 broader. 



Record of specimens: Lake Pueyrredon, base of Tertiary, 12 sp. 



Distribution: v. Ihering does not give a locality, but simply states that 

 this species comes from the Patagonian formation. Two individuals, sent 

 by him to the Princeton Museum, are labelled : Santa Cruz. 



Affinities: the genus Bouchardia is represented so far only in the recent 

 seas, and the typical species, B. tulipa (Blv.) is found on the coast of Brazil. 



MOLLUSCA. 



PELECYPODA. 



* 



Fam. NUCULID& Ad. 



Gen. NUCULA Lamck. 



22. NUCULA PATAGONICA Philippi. 



Plate XXV, Fig. ;. 



1887 N. pat. Philippi, Tert. & Quart. Verstein. Chiles, p. 198, pi. 41, f. 8. 

 1897 N. tricesima v. Ihering, in: Rev. Mus. Paul., v. 2, p. 243, pi. 4, f. 

 21, pi. 5, f. 27. 



1899 N. pat. v. Ihering, in: N. Jahrb. Min. Geol. Pal., p. 15. 



1900 N. pat. Ortmann, in: Amer. Journ. Sci., v. 10, p. 379. 



Shell thick, very convex, almost triangular, oblique, apex forming almost 

 a right angle. Posterior dorsal margin slightly convex, forming with the 

 lower margin a strongly curved posterior angle. Anterior dorsal margin 

 slightly concave, anterior end a little produced, and sharply curved. Sur- 

 face smooth, with concentric lines of growth. Hinge teeth in two rows 

 meeting at a right or slightly obtuse angle, anterior row consisting of ca. 

 8, posterior of ca. 11-13 teeth. No crenulations on inner side of ventral 

 margin. 



