148 



Miscellaneous. 



MISCELLANEOUS. 



ON SUBSTANCES INCLOSED IN AGATE. 



To Richard Taylor, Esq. 



Bulford, June G, 1 84.'L 



Sir, — I send you a sketch of some bodies contained in a brownisFi 

 agate which I have, so nearly resembhng those rejiresented in the 

 plate illustrating the paper by Karl Mueller, M.D., translated and 

 communicated by the Rev. M. J. Berkeley *, that I cannot resist 

 troubling you with my ideas on the nature of those bodies repre- 

 sented in figure 10 of your plate. Many of those in my agate are 

 precisely of similar forms, but I have only figured those which illus- 

 trate my idea of their nature. 



I believe them to be imperfectly formed crystals, probably of red 

 oxide of iron, as their colour is so precisely similar to that substance. 



No. 1. is, I think, evidently an imperfectly formed octohedron 

 with rounded edges, or rather several imperfect crystals of that form 

 superimposed on each otlier, as represented at figure 6 and 6 a. 



The other figures more nearly resemble the figures in your plate. 



No. 4. shows an imperfect facet, but the lines hounding the angles 

 of the crystal in all the other figures are curvilinear, and give them. 

 a rounded appearance. 



The general description of the bodies seen by M. K. Mueller so 

 nearly tallies with those in my agate, that I can scarcely doubt of 

 their identity. Your obedient servant, 



A. SOUTHBY. 



DESCRIPTION OF WOODCUTS. 



Figs. I, 2, .3, 4, 5. Various bodies contained in the agate 7 at B. 



Fig. 7, A. A band in the agate composed of red matter, evidently of the same 



substance of which ], 2, 3, 4, 5 are formed. 

 Figs. 6 and 6 a. represent a crystal which shows some general resemblance 



to the bodies figured above. 



ON THE DEVELOPMENT OF THE CRAY-FISH. BY M. JOLY. 



Encouraged by the Academy of Sciences to continue my re- 

 searches on the freshwater Crustaceans, I first devoted my attention 

 to the embryogeny of the cray-fish, Astacus fluviatilis, Gesner, on 

 * See Annals, vob xi. p. 415. Plate X. — Ed. 



