PEOCEEDINGS 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, and 25 parts glycerine. To prepare 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 (finely 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, inxt in a crucible well ? luted and ex-pose in a white lire. Then leach with boiled water and let crystallize. As the caustic baryta so greedily absorbs the carbonic acid from the air, I give this simi)le 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. Bated, Secretary Smithsonian Institution, Washington, D. C. JLIST OF FIJ^HEJ^ COI.I^ECTEI> BV I.IEUT. HENRV E. NICHOLS, U. 8. N., I!V THE Gri.F OF CALIFORNIA AND OIV THE WEST COAST OF LOUVER CALIFORNIA. WITH DESCRIPTIONS OF FOLR NEW^ SPECIES. By DAVID S. JORDAi\ and CHARLES H. OILBERT. 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.