210 PROCEEDINGS OF THE 



of sharp scissors; and when this is done, the specimen may 

 be considered finished. The fronds of the Polyzoa being 

 generally of a greyish-white colour, they contrast very favourably 

 with the black ground of the asphalt ; and the manner in which 

 the surface of the celluliferous faces of the fronds can be examined 

 over their whole extent, renders this method of treating them 

 very satisfactory. The genera from our soft shales that I have 

 had an opportunity of operating upon, are the several species of 

 FenesteUa, Actinostoma, Synodadia, and Glaziconome, and these have 

 all turned out well. I have also used this method for exposing 

 the outer surface of some of the Aviculopectens, and other shells 

 which were adherent by their rough faces to the stone, and I find 

 it answers very well. 



Before the discovery of treating the larger fronds of the 

 Polyzoa by the asphalt process, when we wanted to examine the 

 celluliferous faces of the various species, we were content with the 

 fragments of the broken up fronds from the soft weathered shales. 

 When these fragments were collected, they were found to be often 

 coated by a thin layer of clay. In order to remove this, I have 

 adopted the following plan : — I pick out of the shale all the 

 fragments to be examined ; I then take a glass slide, and coat 

 it with a layer of thin gum ; next, with the forceps, lifting the 

 fragments of the Polyzoa and placing them on the gum, with the 

 celluliferous face uppermost. When this is finished, I allow the 

 gum on the slide to dry slowly for a day or two, until it is quite 

 hard ; I then place the slide in a saucer filled with water, brushing 

 the specimens gently and quickly with a tooth-brush until they 

 are quite clean, the gum holding the specimens securely, while the 

 washing improves the appearance of the cells. The slide may then 

 be left in the water until the fragments are melted ofi", when 

 they can be easily collected with a soft hair pencil, and dried 

 on blotting paper, after which they are ready for mounting on 

 slides for microscopic examination. I have found this to be a 

 good method for cleaning fragments of Polyzoa only to be had 

 as weathered specimens in the shales, and they form beautiful and 

 interesting cabinet objects for microscopic investigation. 



