XII 



CONTENTS. 



Plate III. 7. Estheria Clarkii 



8. Estheria Belfragei 



9. Lepidurus glacialis . . 



10, Apus sequalis 



Plate IV. 11. Artemia gracilis 



12. Branchipus Coloradensis. 



13. Streptocephalus Texanus 



racing page — 

 ■■■" i 622 



622 



REPORT ON THE AMrHIPOD CRUSTACEANS, BY S. I. SMITH. 



Plate I. Hyalella inermis. 



1. Female ; lateral view, enlarged 16 diameters 



2. Male; terminal portion of one of the second pair of 



thoracic legs seen from the outside, enlarged 50 diam- 

 eters. 

 Hyalella dentata. 



3. Adult male; terminal portion of one of the second pair 



of thoracic legs, seen from the outside, enlarged 50 { g^g 

 diameters. f 



4. Young male ; 3.7""^^ long ; terminal portion of the corre- 



sponding leg, enlarged 50 diameters. 



5. Adult male ; maxillipeds, seen from above, enlarged 80 



80 diameters. 



6. Adult male ; one of the first pair of thoracic legs with 



its epimeron, seen from the outside, enlarged 50 diam- 

 eters. 

 Plate II. Gammarus robustus. 



7. Female ; lateral view, enlarged 5 diameters 



8. Male; flagellum of one of the antennte, enlarged 25 



diameters. 



9. Male; terminal j)ortiou of one of the first pair of thor- 



acic legs, seen from the outside, enlarged 25 diam- 

 eters. 



10. Male; same portion of one of the second pair of thoracic 



legs, enlarged 25 diameters. | 



11. Female; terminal portion of one of the- first i^air of ( g-.^ 



thoracic legs, seen from the outside, enlarged 25 diam- 

 eters. 



12. Female; same portion of one of the second pair of 



thoracic legs, enlarged 25 diameters. 

 Gammarus limnseus. 



13. Male, from lake near Long's Peak ; terminal portion of 



one of the first pair of thoracic legs, seen from the 

 outside, enlarged 20 diameters. 



14. Male, from the same locality ; same portion of one of the 



second pair of thoracic legs, enlarged 20 diameters. J 



SKETCH OF THE METHODS OF SURVEY, BY JAMES T. GARDNER. 



"Sketch showing the primary and secondary triangulation of 1873 627 



THE ELEVATIONS OF CERTAIN DATUM-POINTS, BY JAMES T. GARDNER. 



Map showing the railroad and canal lines used in the determination of elevations 660 

 Preliminary map of Central Colorado, showing the region surveyed in 1873 682 



"WOOD-CUTS IN TEXT. 



REPORT ON THE DIPTERA, BY C. R. OSTENSACKEN. 



On page- 

 Wing of Bibiocephala 564 



DESCRIPTION OF A LERN^AN CRUSTACEAN, BY A. S. PACKARD, JR., M. D. 



Achtheres Carpenter! 612 



THE TELLURIDE ORES OF THE RED CLOUD AND COLD SPRING MINES, GOLD HILL, BY 



B. SILLIMAN. 



A, porphyry-dike, with B, C, veins with gold and tellurium ores 688 



