48 
GEOLOGY 
Locality. — This species has not been pointed out before in America. I found it at Pecos vil- 
lage and on the, summit of the Sierra de Sandia; but it is not very abundant. 
Explanation of figures. — Plate V, fig. 6. Front view of specimen found at Pecos village. 
» V, fig. 6 a. The same, side view. 
PRODUCTUS PYXIDIFORMIS de Kon. 
Plate VI, fig. 3,3a. 
Description. — Shell very gibbous, very transverse and of moderate size. Dorsal valve very gibbous, divided 
in the middle by a deep hollow sinus. Sides abrupt and rounded. Beak pointed, slightly recurved and prolonged 
beyond the cardinal edge. Surface covered with numerous elongated tubercles.- Concentric folds traverse the dor- 
sal valve near the beak and render the surface undulating. The ventral valve is plane, excepting two slight lateral 
and oblique depressions, that give place to a small elevation corresponding to the sinus of the opposite valve; it is 
covered with small cavities regularly distributed on the concentric wrinkles of the beak. 
Locality. This species was clearly pointed out for the first time in 1847 by L. de Koninck; 
see: Monographic du genre Productus, p. 116, pi. 11, 12 and 16; who had it from Belgium, from 
Yorkshire and from Ireland. It had not been met with in America, when I found it near the vil- 
lage of Tigeras, New Mexico; it appeared to be quite common. 
Explanation of figures. — Plate VI, fig. 3. Front view. Tigeras specimen. 
» VI, fig. 3 a. Same, side view of the ventral valve, The two lateral depressions 
and the small elevation are not well drawn , though they are 
very well developed in the specimen. 
PRODUCTUS PUSTUUOSUS Phill. 
Plate VI. fig. 1 . 
Description. — The following is the description given of this fossil by my honorable friend Professor John Phil- 
lips of Oxford University. « Rotundo-quadrate, gibbous, ear angular, furrowed, spineless; transverse undulated 
« wrinkles, bearing numerous scattered spines, which become more and more depressed toward the margin)). (See; 
Geology of Yorkshire; Part II; Mountain Limestone district; p. 2i6; pi. VII , fig. 15. See for a longer and more mi- 
nute description: Monographic du genre Productus , by de Koninck; p. 118; pi. 12. 13 and 16.) 
Locality. — This species had not been met with before in America. I found only one spe- 
cimen well preserved at Tigeras, New Mexico. 
Explanation of figure. — Plate VI, fig. I. Specimen natural size, front view. 
PRODUCTUS PUNCTATUS Marl 
Plate VI , fig. 2. 
Description. — Shell rotundo-quadrate; less gibbous than the p. pustulosus \ a shallow mesial sulcus extends from 
about six lines from the beak to the front margin. Surface of both valves concentrically marked by flat imbricating 
sub-regular bands of growth, each closely and variously punctured with numerous rows of perforated spinulosae. 
See for more details: Monographic du genre Productus, page 123; and also; British Paleozoic Fossils, by M*" Coy; 
page 469. 
Locality. — This species is not rare in the Rocky mountains. 1 have seen it at Tigeras, Pe- 
cos village and in the Sierra de Mogoyon. 
Explanation of figure. — Plate VI , fig, 2, Front view. Tigeras specimen. 
ORTHIS PECOSII n. sp. 
Plate VI , fig. 14 . 14 a , 14 b. 
Description. — Shell oval , sides semi-elliptically rounded , lateral and front margins in one plane ; beak obtu.se, 
prominent; mesial fold indistinct; surface radiatingly striated . very finely, with thread like striae. 
