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APPENDIX. 



I PROPOSE here to give a very brief account of two groups of Monti- 

 culiporoids which have been described by Dr Dybowski (Die Chse- 

 tetiden, 1877), under the names of Treviatopora, Hall, and Dittopora, 

 Dyb. Not having access to any specimens which I could refer to 

 either of these groups, I am able to do little more than to reproduce 

 the essential features of Dybowski's descriptions, and to append two 

 or three illustrations in elucidation of these. 



Trematopora, Hall (Dybowski). 



Under the name of Trematopora, Hall, Dybowski describes a num- 

 ber of Monticuliporoids, to which he assigns the following characters : 

 The corallum is polymorphic ; the corallites thick-walled, cylindrical, 

 in cross-section elliptical. The thick-walled elliptical calices project 

 slightly above the general level of the " coenenchyma." The "coenen- 

 chyma" appears superficially to be compact, but is formed of transverse 

 lamellae, which unite with one another to form a network. The Avails 

 of the corallites consist of very delicate, closely contiguous lamella, 

 which are directly continuous with the individual meshes of the '' coen- 

 enchyma." Within the walls run very narrow hollow canals (" Wand- 

 rohrchen"= " spiniform corallites"). Tabulae are present (Die Chae- 

 tetiden, p. 69). 



The forms included by Dybowski under this head are T. colliculata, 

 Eichw. sp., T. ciugulata, Dyb., T. pustiilifcra, Dyb., and T. variabilis, 

 Dyb. 



How far Dybowski may be correct in referring the above forms to 

 the genus Trematopora, Hall, is a matter upon which I do not feel com- 

 petent to pass an opinion ; since I am not aware that any descriptions 

 of the minute structure of this genus, taken from authentic American 

 examples, have as yet been made public, either by the distinguished 



