PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 273 



cent, zinc oxide. It becomes as hard as horn. A softer mass consists 

 of 50 parts glue, 25 parts wax, an<l 25 parts glycerine. To prei)are the 

 mass, dissolve the glue in warm glycerine, then add the wax, and lastly 

 the metal oxide. 



R. Martin, in Sonneberg, mixes 20 to 100 parts zinc oxide with 5 to 

 10 parts tartaric acid or calcined alum and 100 parts starch (tinely 

 powdered), and the required quantity of water to form the casts. If 

 these articles are at a temperature below 15^ Celsius and are poured 

 in warm molds, the cast becomes brittle, but is at once made plastic by 

 being placed in a water-bath of 50°. Then give the casts a surface 

 which permits washing by collodion, which is mixed with a solution 

 of wax in ether. 



My method of preparing caustic baryta is: Take carbonate baryta, 

 pulverize and mix with charcoal, put in a crucible well ? luted and ex- 

 pose in a white tire. Then leach with boiled water and let crystallize. 

 As the caustic baryta so greedily absorbs the carbonic acid from the 

 air, I give this simple cheap method, so that your department can often 

 make the caustic baryta new, when the old has turned into carbonate 

 baryta. 



I have written these various methods and you can select what pleases 

 you. 



I shall be under great obligations to you, if you will send me the sur- 

 vey and publication when ready. 



I remain, dear sir, yours very truly, 



ANTHONY PIRZ. 



Hon. Spencer F. Batrd, 



Secretary SmitMonian Institution, Washington, D. C. 



f.IST OF FISHES COI-l^ECTED BY I.IEUT. HEXRV E. IVICIfOI^S, U. 

 8. IV., IN THE GITI.F OF C!Al.IFORIVIA AIVD 0!\ THE WEST <10A»T 

 OF I>01VER CAEIFORNIA, WITH DESCRIPTIO^VS OF FOUR ISEW 

 SPECIES. 



By DAVID S. JOISDAIV and CHARLES H. GILBERT. 



The specimens of fishes collected by Lieut. Henry E. Nichols, com- 

 mandant of the United States Coast and Geodetic Survey Steamer Has- 

 sler, in his voyage along the coast of Mexico and Central America, have 

 been already noticed by us on page 225 of the present volume of the 

 Proceedings of the United States National Museum. On the north- 

 ward voyage of the Hassler (January-March, 1881), Lieutenant Nichols 

 made another collection, also of much importance. A list of the species 

 obtained, with their numbers as recorded in the register of the museum, 

 is given below. 



It will be noticed that all the species obtained from the west coast of 



Lower California belong to the Californian fauna, while nearly all of 



those obtained within the Gulf are members of the tropical fauna of the 



west coast of Mexico. It is a fact worthy of note that very few of the 



Proc. Nat. Mus. 81 18 Jan. 20, 1 882. 



