M. Bronn on the Laws of Evolution of the Organic World. 175 



largely developed and thickened with mud, &c. In some of my 

 specimens, which have been kept in dilute alcohol, the mud is 

 removed, and the colletoderm appears as a transparent struc- 

 tureless coat covering the polypes and the corallum, and quite 

 distinct from the latter. I have detected this membrane also on 

 the body of the polype of Coryne decipiens (Dujardin) and Clava 

 repens (mihi), so that Bimeria is not singular amongst Zoophytes 

 in the possession of an overcoat. 



2. Eudendrium bacciferum (Allman), Garveia nutans (mihi). 



This Zoophyte was also described and figured by me before 

 the Royal Physical Society, in the 'Witness/ and in the 'Edin. 

 New PhU. Journal/ under the same dates as Bimeria vestita. 



3. Coryne Briareus (Allman), Coryne implexa (mihi), Tubularia 

 implexa (Alder). 



The corallum, destitute of polypes, of Coryne implexa was de- 

 scribed by Mr. Alder, in his Catalogue of Zoophytes of the 

 Northumberland Coast, under the title of Tubularia implexa. 

 In August 1859 I found it with its polypes, and described and 

 published it together with Bimeria vestita. I have, since the 

 publication of C. Bi'iareus by Professor Allman, placed my spe- 

 cimen of C. implexa in the latter gentleman's hands ; and he is 

 of opinion that it is identical with his. He has, however, unfor- 

 tunately lost his specimen ; so that the coralla cannot be com- 

 pared with each other. The corallum of C. implexa is composed 

 of two very distinct coats, the inner one ringed and horny, the 

 outer one thin, membranous, and not ringed. The latter ap- 

 pears to consist of "colletoderm" in an indurated state. 



All the above-mentioned Zoophytes exist in the same localities 

 — the Bimer and Garvey Rocks at Queensferry, Firth of Forth. 



Edinburgh, August 1, 1859. 



XVIII. — On the Laws of Evolution of the Organic World during 

 the Formation of the Crust of the Earth. By H. G. Bronn. 



[Concluded from p. 90.] 



III. Results concerning the relations which connect the present 

 state of the organized kingdom with its geological states. 



In all that precedes, we have taken into consideration not 

 only the ancient, but also the present state of things. We have 

 traced the modifications presented to us by the organic world in 



is very indestructible, and not coagulable by dilute spirit. It is secreted 

 directly from the ectoderm of the zoophyte, the hard corallum being after- 

 wards secreted beneath it. It is probably a modification of chitine. 



