194 TJie American Geologist. September, 1900 
Walcott, C. D. 
The work of the United States Geological Survey in relation to the 
mineral resources of the United States. (Trans. Am. Inst. Min. Eng., 
vol. 30. Wash. Meeting, Feb. iqoo,) 
Weed, W. H. 
The enrichment of gold and silver veins. (Trans. Am. Inst. Min. 
Eng., Washington meeting, Feb. 1900.) 
Weed, W. H. 
Enrichment of mineral veins bv later metallic sulphids. (Bull. Geol., 
Soc. Am. vol. II. pp. 179-206, April, 1900,) 
Willis, Bailey, 
Work of the United States Geological Survev, 1899-1900. (Science, 
vol. 12, pp. 241-246, Aug. 17, 1900.* 
Williston, S. W. 
Some fish teeth from the Kansas Cretaceous. (Kans. Univ. Quart, 
vol. 9, pp. 27.42, 7 pis., Jan. 1900.) 
WJnchell, A. N. 
^^ Etude mineralogigue et petrographique Ides roches gabbroiques de 
J'Etat de Minnesota, Etats Unis, et plus specialement des anorthosites. 
(These presentee pour obtenir le titre de docteur de I'universite de Paris. 
162 pp. 9 plates, Paris,. July, 1900.) 
Woodworth, J. B. 
Glacial origin of older Pleistocene in Gay Head cliffs, with note on 
fossil horse of that region. (Bull. Geol. Soc. Am., vol. 11, pp. 455-460. 
June, 1900.) 
Woodworth, J. B. 
Vertebrate footprints on Carboniferous shales of Plainville, Mass, 
(Bull. Geol. Soc. Am., vol. 1 1, pp. 449-454, pis. 40 41, June, 1900.) 
COPxRESPONDENCE. 
Further Note on Uintacrinus. In the August, 1899, number 
of this journal I announced the discovery of a dicyclic base in certain 
specimens of Uintacrinus socialis Grinn. Further study of the material 
in my hands has disclosed the nature of the tegmen of this genus hith- 
erto unknown. It proves to have a disk consisting of an integument or 
skin, which is black in the fossil state, thickly studded with calcareous 
spicules of irregular form and arrangement, and not in contact with 
each other. The center of the disk is occupied by a large anal tube, 
while the mouth is at the margin, and from it, the ambulacra follow the 
periphery of the disk, connecting with the several arm branches. Such 
a form of tegmen has not been known in any crinoid, recent or fossil, 
except in the living comatulid genus, Actinometra, with which it is in 
all essential particulars apparently identical. As in that genus, Uinta- 
crinus, has no calcified ambulacral skeleton, either on the disk or arms. 
I give this preliminary note of the discovery for the information of in- 
vestigators. A full description of this and other structures of this cri- 
noid will appear in a fully illustrated paper now about to go to press. 
East Las Vegas, N. M. Frank Springer. 
