360 
MINERALOGY: LARSEN AND WELLS 
origin of the oocyte in Dineutes nigrior and in Dytiscus is in the number 
of differential mitoses; in Dineutes nigrior there are only three (fig. 6) 
whereas in Dytiscus there are four. 
As a result the oocyte of Dineutes nigrior is accompanied by only 
seven nurse cells, that of Dytiscus by fifteen. The origin and history 
of the oocyte determinant are of considerable interest and importance 
because of their bearing on the subject of the physical basis of heredity. 
A more detailed study of our material is now being made and the ovaries 
of Dineutes nigrior and of several other species promise to furnish a 
means of clearing up the details of differential mitoses in these insects. 
Debaisieux, P., Les debuts de I'ovogenese dans le Dytiscus marginalis, La Cellule, 25 (1909). 
Giardina, A., Origine dell' oocite e delle cellule nutrici nel Dytiscus, Intern. Monatschr. 
AnaL, Leipzig, 18 (1901). 
Govaerts, P., Recherches sur la structure de I'ovaire des insects, Arch, hiol., Paris-Bruxelles , 
28 (1913). 
Giinthert, T., Die Eibildung der Dytisciden, Zool. Jahrb., Jena, 30 (1910). 
Hegner, R. W., Studies on Germ Cells, I and II, /. Morph., Boston, 25 (1914). 
Kahle, W., Die Paedogenese der Cedidomyiden, Zoologica, Stuttgart, 21 (1908). 
Kern, P., Ueber die Fortpflanzung und Eibildung bei einigen Caraben, Zool. Anz., Leip- 
zig, 40 (1912). 
Korschelt, E., Ueber die Entstehung und Bedeutung der verschiedenen Elemente des 
Insectenovariums, Zs. wiss. Zool., Leipzig, 43 (1886). 
Maziarski, S., Sur la persistance de residus fusoriaux pendant les nomb reuses generations 
cellularies du cours de I'ovogenesese de Vespa vulgaris. Arch. Zelljorsch., 10 (1913). 
WiU, L., Oogenetisclie Studien, I. Die Entstehung des Eies von Colymbetes fuscus, 
Zs. wiss. Zool., 43 (1886). 
^ We are indebted to Mr. A. W. Andrews for the identification of this species. 
2 Mr. R. W. Hegner is indebted to the Bache Fund for assistance in preparing the material 
on which this report is based. 
SOME MINERALS FROM THE FLUORITE-BARITE VEIN NEAR 
WAGON WHEEL GAP, COLORADO 
By Esper S. Larsen and Roger C. Wells 
U. S. GEOLOGICAL SURVEY, WASHINGTON. D. C. 
Received by the Academy, May 27, 1916 
In the summer of 1912 Messrs. W. H. Emmons and E. S. Larsen^ made 
a hasty examination of the fluorite-barite vein which passes through the 
hot springs near Wagon Wheel Gap, Colorado. Since that time this 
vein has been extensively prospected and a considerable amount of 
fluorite has been produced. In the summer of 1915, in the course of the 
reconnaissance geologic study of this region under the direction of Dr. 
Whitman Cross, Mr. Larsen made another brief visit to the deposit and 
collected two specimens of material not before recognized in the deposit. 
