Mr. IL J. Carter on the Stromatoporidce. 317 



maining on the layers internally where the latter have been 

 separated or are surmounted by hollow spaces, almost identical 

 with what I have figured of Hydractinia ecldnata^ H. calcarea, 

 and the fossil species H. ])liocena respectively (Ann. 1877, 

 vol. xix. pi. viii. figs. 1, 4, and 9, c, d). 



So that I am quite prepared, under these circumstances, not 

 only not to find the " tubes " in Stromatopora^ as stated by 

 Lonsdale, but to find in their stead indications of the existence 

 of minute holes on the surface, as in tlie Hi/dractinice^ where 

 they do not exceed the l-600th of an inch in diameter. 



Hall has figured them in his Stromatopora concentrica^ but 

 unfortunately has not added the measurement (' Palasontology 

 of New York,' 1847, vol. ii. p. 136, pi. 73. figs. 1 h and 1 c) ; 

 and I have often seen what I take to be the same foramina, 

 but only in one instance where it seems to admit of no doubt ; 

 and this was in a specimen of (tome) *S'. concentrica^ Avhich came 

 from the interior of a Beekite found near Torbay, and now in the 

 possession of Mr. Vicary, of Exeter, who kindly lent it to me 

 for examination. The transformation of the Sti-omatojwra here 

 into silex has been attended by such a definition of structure 

 that the indication of the original holes or calicles which con- 

 tain the animals is particularly convincing in one part, where 

 tliey are filled with transparent silex, presenting respectively a 

 white or flocculent centre. They are situated between the 

 points of the " rods" which appear on the surface, are all of 

 the same size, and measure l-180th inch in diameter, while the 

 white portion in the centre is l-360th inch in diameter, each of 

 which exceeds in this respect the diameter of the holes of the 

 calicles (that is, the holes which permit the exit of the poly- 

 pites) in the recent species of Hydractinia. 



Thus we appear to arrive at the nature of the animal of 

 Stromatopora^ the signification of the stelliform groups of 

 vessels, and the successive development of the coenenchyma 

 through Hydractinia, Millepora alcicornis, and Caunopora. 



The general form of the Stromatoporidse would appear to have 

 been indefinite ; that is, like reef-corals generally, they grew 

 over every thing with which they came into contact, transform- 

 ing some things into tlieir own structure, and simply enveloping 

 others, after the manner of Hydractinia, progressing by suc- 

 cessive lamination ; so that, wliether weathering as in Cauno- 

 pora or as in Stromatopora, this was, as in corals, the most pro- 

 minent feature of the mass, — sometimes thin, spreading, and 

 incrusting (as in >S^. granidata, Nich.), at others more or less 

 massive and erect (as in Caunopora and Stromatopora concen- 

 trica). The most symmetrical specimen of the latter kind that 

 I have seen is in tlie possession of Mr. Vicary, of Exeter, and 



