F. KITTON ON SOME NEW DIATOMACE^. 17 



Japan (of which some cases had been sent to the Fisheries Exhi- 

 bition at South Kensington) for the purpose of making a micro- 

 scopic analysis of the contents of their stomachs, and as his 

 modus operandi may be of service to others who are desirous 

 of examining the stomachs of Oysters and other mollusca, I 

 give his directions for their preparation : " After opening the tin 

 and pouring off the liquid contents, I empty out the Oysters and 

 pick out the stomachs (which look like dark little sacs, and as a 

 rule are free, or only partially surrounded by a little fatty matter, 

 which is easily taken off). I then heat in a flask to boiling point 

 five or six ounces of nitric acid, in which I drop one by one the 

 stomachs, waiting until each is dissolved before adding another. 

 After all have been dissolved I add an ounce of hydrochloric acid, 

 and continue the boiling for five minutes, dropping in at intervals a 

 little bichromate of potash. I now fill up the flask with hot water 

 and empty the whole into a large beaker, filling up with the hot water 

 (the fat rises to the surface, and on cooling congeals on the top, 

 and is easily skimmed off). I wash away the acid, using hot water, 

 and boil in soap and water according to Prof. H. L. Smith's direc- 

 tion.* If this docs not get rid of the organic matter, I boil in 

 sulphuric acid and chlorate of potash." 



In addition to the numerous more or less well-known species 

 found in these stomachs, Mr. Sturt detected several valves of an 

 Aulacodiscus, which he exhibited at a meeting of the Club, held 

 Dec. 14, 1883, as A. angulatus, Grev. Having some doubt as to 

 the identity of the two forms, he forwarded to me for examination 

 several specimens of the form he had found, and, on placing them 

 under the microscope, I saw that they differed from any published 

 species with which I was acquainted, and a 1 so from any of the 

 numerous specimens in my cabinet. Under a low power they 

 somewhat resembled A, angulatus and A. am o? mis, Grev., but a 

 greater amplification (-|) showed the resemblance to be very slight, 

 the difference being, in my opinion, of sufficient importance to con- 

 stitute a new species. I, therefore, have much pleasure in naming 

 it after the discoverer. 



Aulacodiscus Sturtii, n. sp. F.K. Frustule cylindrical, valve 

 with a large central elevation (usually flat on the toj>), not 

 bullate below the processes, processes placed on the angles of 



* The water used for washing must be filtered rain or distilled water, and 

 free from all trace of acid. — F. K. 



Joukn. Q. M. C, Series II., No. 9. c 



