AND GLYPnASTRiEA, DUNCAN (1887). 205 



genus the original Tertiary species of d'Orbigny and Edwards 

 and Haime, on which its characters were originally based, and 

 which from 1849 to 1861 were the only species included in it. 



It would have been quite in accordance with precedent to have 

 amended the diagnosis of Septastrcea, if the typo specimen showed 

 that the definition given of it by d'Orbigny and by Edwards and 

 Haime was not so full or so accurate as it ought to be ; but it is a 

 decided violation of the ordinary rule, and does great injustice to 

 the author of a genus to appropriate what he claims to be the 

 type species for a new genus, and to leave in its place species 

 which are not generically related to the forms which the author 

 proposed to include in it. It seems to me, therefore, that the genus 

 Glyphastrcea, being based on Septastrcea Forbesi, the type species of 

 d'Orbigny's genus Septastrcea, cannot be regarded as valid, and 

 must therefore lapse. 



The principal object which I have had before me in thus tracing 

 out in some detail the history of Septastrcea is to show that, what- 

 ever may be the characters of the genus, they have been based upon 

 corals from the Miocene formation of Virginia and Maryland, and, 

 further, that Septastrcea Forhesi, E. & H., is the type species, and 

 one of the original specimens of it is in the British Natural History 

 Museum. I now purpose giving a detailed description of the type 

 form, comparing it also with the other specimens which have been 

 lent to me, so as to place the characters of Septastrcea on surer 

 ground than hitherto. I may remark that most of the specimens 

 are in excellent preservation, retaining their structures as per- 

 fectly as in recent corals, and in certain respects better adapted 

 than recent corals for the study of minute structural details. Their 

 mineral constitution appears to be likewise unaltered*. 



Septastrcea Forhesi. — Outer Form. This is variable in different 

 specimens, which are for the most part upright, cylindrical, or 

 compressed, palmate stems or expansions, from which short, stumpy 

 branches, with rounded blunted extremities, proceed irregularly. 

 The branches are either simple ordichotomons. In one compressed 

 palmate specimen the uneven margins merely show small depressed 

 cavities from which branches have evidently been broken off. No 

 specimen which I have seen is complete ; the basal portion of the 

 corallum is always wanting, so that the mode of attachment and the 

 character of the young form cannot be known. In all the speci- 

 mens of S. Forhesi the entire surface exposed, with the exception 

 of the fractured portions, is covered with the summit walls and 

 calicos of the corallites, which are all approximately in the same 

 general surface-plane and in contact with each other. The lateral 

 walls of the corallites are only shown in the fractured portions of 

 specimens. 



Mode of Growth and Increase. — The exclusive mode of increase, 



* Prof. Duncan has indeed stated that the Maryland specimen which he 

 examined is siliceous (Quart. Journ. Geol. Soc. vol. xliii. p. 25) ; but on testing 

 this same specimen with acid, I find every indication that it is of carbonate of 

 lime, the same as the type and other specimens in the British Museum. 



