68 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [JuilG 14, 



has been applied to two different modes of composition : — one, in 

 wliich tubes springing from a centre form successively funnel-shaped 

 layers or rows, the newest being developed within the one which 

 preceded it, as in the fossil represented in Goldfuss's figure 4c, pi. 27 

 , {Calamopora polymoiyha) ; while by the other mode, the newest layer 

 is constructed without the next older, constituting a cylindrical crust, 

 the whole mass being composed of concentric layers. Figure 13, 

 pi. 10 (Ceriopora tuhiporacea) of the ' Petrefacten,' exhibits appa- 

 rently such a structure (consult p. 35). Both those fossils M. de 

 Blainville removed to Lamarck's Alveolites, which, he states, as well 

 as that authority, is composed of layers enveloping one another (Man. 

 d'Actinol. p. 404). If the structure exists in the original species of 

 Heteropora, it probably conformed to the funnel-shaped plan (Pe- 

 tref. pi. 10. fig. 5 h) ; whereas in the lower greensand fossil it exhibits 

 concentric layers. In MM. Koch and Dunker's work on the oolitic 

 formations of northern Germany f, a coral referred to Heteropora 

 displays in one of its illustrative figures (pi. 6. fig. 14 c) a concentric 

 composition closely resembling that observable in some fractured 

 branches of the English fossil (fig. 9 nob.) ; and it possesses a diversity 

 of size in the pores. Whether that body has an aggregate of essential 

 structures similar to that of the one under examination, no opinion 

 can be hazarded ; but supposing such an identity could be established, 

 and it is not impossible, still, so far from the two fossils being distinct 

 species of Heteropora, it would be necessary to sever the German pro- 

 duction from the genus. Again, the Ceriopora titbiporacea of Gold- 

 fuss (pi. 10. fig. 13) alluded to before, displays in the transverse section 

 a concentric composition closel}^ resembling that shown in transverse 

 slices of the lower greensand coral (fig. 10) ; but in the figures quoted, 

 only one sort of aperture is delineated, and there are no proofs of 

 continuous tubular cavities. M. de Blainville removed Cer. tuhipo- 

 racea to Alveolites, as already stated ; but it is not necessary to in- 

 quire if the fossil under discussion belong to the same genus ; because, 

 whether the second species described by Lamarck {Al. suhorhicularis, 

 t. ii. p. 286), the first being of a doubtful nature, or the recent spe- 

 cies {jLL incriistans, p. 287, no. 4), be assumed as the type, neither 

 of them has the structures of the Isle of Wight coral. 



As a summary of differences between Heteropora and the subject 

 of this notice, it may be stated, that in the tubes of //. anomalopora 

 not a trace of transverse laminse is shown, nor are such plates alluded 

 to in the descriptions of any species ; whereas, in the specimens re- 

 presented by fig. 6 and 6*, they are often very conspicuous : the cha- 

 racter expressed by M. Goldfuss's figure .5 is that of the tube of an 

 Ascidian polype ; while the laminse in the section would intimate an 

 Anthozoan inhabitant. Whatever may be the nature of the minor 

 pores in Heteropora, they clearly belong to a peculiar, cellular struc- 

 ture in the greensand fossil : differences in the enveloping layers have 

 been already mentioned ; but it must be added, that in the English 

 coral the concentric character is due to a cellular composition ar- 



•j- Beitrage zur Kenntniss des Norddeutschen Oolithgebildes, &c., 4to, 1837. 



