•-'..'" 



tit form of water bath, 

 sed by Dr. Mayer. 



small brass box ] 



£. 9 " 



ind 



high. 



The tube a, through which the 

 water is received, and the rod b 

 serve as handles. The receiving 

 tube is closed by a cork provided 

 with a glass tube for the escape 

 of steam, which is bent in the 

 form of a siphon to protect 

 against dust. One and a-half 

 centimeters from the base of the 

 box is an oven (o) .f m high, and 

 I2 cm long, which passes com- 

 pletely through the box, and 

 serves for warming the slides 

 when shellac is used. Above 

 are seen two circular basin-like 

 pits (p) 5. 5 cm 



for 



the 



L paraffine holders. These are 



covered by circular plates of glass. There' are also six tubular 

 pits, one for a thermometer (/), the others for glass tubes. 



This water bath will be found useful for other purposes than 

 those of imbedding and mounting. It will of course be under- 

 stood that the purpose in giving its exact dimensions is simply 

 to furnish a guide where one is required. There are at least two 

 important advantages offered by this water baih over those in 

 general use, viz., the slides are protected from dust, and the par- 

 affine is not exposed to the water. 



ON THE HOMOLOGIES OF THE CRUSTACEAN LIMB. 



BY A. S. PACKARD, JR. 



THE following observations are reprinted from an essay on 

 * North American Phyllopod Crustacea, contributed to the 

 forthcoming Twelfth Annual Report of the U. S. Geological and 

 Geographical Survey of the Territories, F. V. Hayden in charge. 

 I am indebted to Dr. Hayden's kindness for the use of the illus- 



