46 
GEOLOGY 
sance and Survey of a Railway route from Mississippi rivev near 35"' parallel north latitude to Pacific Ocean ; 
by Lieut. A. W. Whipple; Washington, 1855 (The latitude of camp N° 96 is 35°, 17', longitude 
112°, 13'.); in the country of the Tontos Indians. 
Explanation of figure. — Plate VI, fig. 5. Front view. Some tubercles are visible; the striae are rather worn. 
PRODUCTUS SEMI-RETICULATUS Mart. 
Plate V , fig. 4, 4 a. — Plate VI, fig. 6. 
Description. — Few fossils are better known or more widely spread than this. De Koninck gives a very minute 
description and history of it in his Monograph of the genus Productus, page 83; plate 8, 9 and 10. Frederick M*" 
Coy gives also an excellent description of it (See : Description of the British Paleozoic Fossils in the Geological Museum 
of the University of Cambridge -, page 471.). As I have not seen the first work of Martin, in which there is a figure 
and description of this Productus, noticed by any Paleontologist, not even by de Koninck, M® Coy or de Verneuil, 
these savants quoting always from the memoir of William Martin entitled: Petrificata Derbiensia; or figures and de- 
scriplions of Petrifactions collected in Derbyshire ; in 4°, 1809; I give here verbatim the description published by Wil- 
liam Martin in 1793. This work is very rare even in England; its title is; Figures and Descriptions of Petrifactions 
collected in Derbyshire , to which are added a systematical list of the Minerals and an introduction to the knowledge of 
Petrifactions in general; Wigan; in 4°, 1793. The Productus semi-reticulalus is found plate 22, fig. 1, 2, 3. The de- 
scription is as follows ; 
« A fossil shell of the genus Anomia , striated in a longitudinal direction , and (in some specimens) set with a few. 
« small distant tubercles; the hinge on a streight line; the under or larger valve convex, the margin produced or 
((lengthened out beyond the extent of the other valve, and in its general form approaching a cylindric figure; the 
((beak small, curved over the hinge; the upper valve flat or slightly concave, very small, and hid, in the fossil 
((State, by the cylindric part of the larger valve. 
((This curious Anomia is found in many parts of Derbyshire; seme of the best specimens, I have seen , 1 col- 
((lected in a mine near Groom-Hill, about four miles south of Buxton.)) 
Locality. — This fossil is very common in the Rocky mountains, the Sierra Madre and the Si- 
erra de Mogoyon. At the village of Pecos near Santa Fe it constitutes almost the whole of a 
bed of limestone two feet thick , and in an hour or two several hundred specimens in good pre- 
servation might easily be collected. It is also very abundant at Tigeras in the Caron of San An- 
tonio, at the very top of the Sierra de Sandia; and at Cedar creek in the Sierra de Mogoyon. 
I have received specimens coming from the borders of the Great Salt Lake, from the sources of 
the Rio Colorado Chiquito in the Sierra Blanca; from the town of El Paso, state of Chihuahua; from 
the junction of the Rio San Pedro with the Rio Gila, Arizona Territory; and lastly from Vancou- 
ver island. 
Explanation of figures. — Plate V , fig. 4. Front view with tubercles , from Pecos village. 
» V, fig, 4 a. Same, side view. 
» VI, fig. 6. Large specimen, front view; from Cedar creek, west of the ex- 
tinct volcano of San Francisco. 
PRODUCTUS COSTATUS Sow. 
Plate V, fig. 5, 
Description. — Shell transversely oblong, with an angular depression in the middle, costated; costae few , broad, 
convex, irregularly unequal, longitudinal and crossed on the rostral portion only by regular concentric wrinkles, 
thus producing a regular reticulate luberculation. Spine cylindrical, strong, a single one on each longitudinal rib. 
For more details see: Monographic du genre Productus, par L. de Koninck; p. 92. 
Locality. — This is a bad specimen, rolled and worn, but still having the characters of the spe- 
cies. I possess some better specimens collected by me in the Sierra de Mogoyon at Cedar creek. 
