No.i549r NEW ORDOVICIAN FOSSILS— WELLER. 559 



HEMIPRONITES TENUISTRIATA, new species. 



Description. — Shell wider tlian long, the valve.s subcquall}' convex, 

 the hinge line a little shorter than the greatest width, the cardinal 

 extremities subangular. Pedicle valve most prominent on the umbo, 

 the beak rather obtuse, the surface sloping from the umbo laterally 

 and anteriorly with a gently convex curve; a slight, scarcely noticeable 

 mesial flattening of the valv^e occurs toward the front, but no mesial 

 sinus is present; cardinal area flat, rather large, with a broad deltidium, 

 the cardinal margins angular. Brachial valve most prominent along 

 the median line, but with no differentiated median fold, the greatest 

 convexity at about the mid-length of the valve, the surface slighth- 

 compressed toward the cardinal extremities. Surface of each valve 

 marked by exceedingly tine strife, which are scarcely visible to the 

 naked eye, about eight occupying the space of one millimeter. 



The dimensions of a pedicle valve are: Length, 10 mm.; width, 

 approximately 17.5 mm.; convexit}^, 5 mm.; height of cardinal area, 

 3 mm. ; length of hinge line, 15 mm. The dimensions of a brachial 

 valve are: Length, 17 mm.; width, 22 mm.; convexity, 5 nun. 



Remarhs. — The specimens of this species in the collection are all too 

 poorly preserved to allow the determination of its generic position 

 with entire satisfaction. The}" have, however, the general form of 

 European members of the genus Ilemipronites., and it is believed that 

 this generic reference is correct, but the nature of the deltidium and 

 the presence or absence of a foramen can not be certainly determined. 

 The genus llemipronites has not been recognized in the American 

 faunas, and is known especially from the Baltic provinces in Russia. 

 The species is evidently congeneric with the shell which Martelli has 

 called OrtJiisina giraldi" and the two species are closely allied. The 

 species here described, however, is somewhat more finel}^ striate, and 

 it seems to be relatively a somewhat broader shell. 



Formation and locality. — Ki-sin-ling limestone, locality 20 C, near 

 Su-kia-pa, province of SsT-ch'uan. 



Order TRILOBITA. 



AMPYX CHINENSIS, nev/ species. 



Description. — (Jranidium sul)semicircular in outline, width 6.8 mm., 

 length 3.5 mm. Glabella prominent, produced anteriorly somewhat 

 beyond the frontal margin, subangular along the dorsal median line, 

 the sides convex and sloping rather abruptly to the dorsal furrows; at 

 the anterior termination of the glabella is the fractured base of a 

 slender cylindrical spine whose length can not be determined, lateral 

 furrows obsolete. Occipital furrow narrow and shallow. Occipital 



f'Boll. della Soc. Geol. Ital., XX (1901), p. 305. 

 Proc. N. M. vol. xxxii— 07 36 



