316 Mr. H. J. Carter on the Stromatoporidge. 



mamillary process, e. g. in Stromatopora polymorplia. This 

 is perhaps best seen in the vertical section, where according to 

 the height of the elevation will be the slope of the vessels. 

 But whatever form this vascularity may present, it cannot 

 alter the function, which, as before stated, is that of the " pro- 

 liferous membrane " or hydrophyton. 



We now come to the calicles of Stromatopora j and as these 

 are the last indications of the animal which formed it, and we 

 have no " tubes " to aid us here as in Caimopora, it will be 

 necessary to give close attention to this part of the subject if 

 the chief object of this communication is to be realized. 



I would here premise that, after Dr. Murie had, with his 

 usual desire to sacrifice every thing to truth, however and by 

 whomsoever elicited, shown me Prof. Nicholson's American 

 specimens of Stromatoyora^ which being as they were found 

 (that is, presenting their natural surfaces much better than 

 might have previously been expected after the contingencies 

 to which they must have been exposed for so many ages since 

 they formed the coenenchyma of living animals), my general 

 impression was that these surfaces were more nearly allied to 

 Hydractmia echinata than to Millepora alcicornis ; and this I 

 find to be confirmed by Prof. Nicholson's following description 

 of his St7-omatopora granuJata (Ann. 1873, xii. p. 94), viz. : — 

 " It forms thin crusts, often occupying very extensive surfaces 

 (3 X 2 ft. X ^ in.). Composed of concentric lamina?, about ten 

 in the space of a line, separated by inteispaces which are mi- 

 nutely broken up into cells by numerous delicate vertical rods. 

 Surface regularly undulating, often raised into chimney-hke 

 or conical elevations, which, however, are never perforated. 

 The entire surface is covered with a fine miliary granulation." 

 To which is added (Ann. 1874, vol. xiii. p. 10), ''the pores 

 consist of minute close-set perforations in a delicate calcareous 

 membrane or surface-layer." 



I examined several specimens of this species, viz. 8. granu- 

 lata, collected by Prof. Nicholson, at Dr. Murie's, and observed 

 that the ^' conical elevations " were essentially like those of 

 Hydractinia echinata ; while in one specimen, where a part of 

 the superficial layer had been taken off, and the vessels of the 

 Stromatopora thus exposed, the latter presented the usual 

 stellate appearance instead of the straggling form in Hydrac- 

 tinia echinata and H. arhorescens (Ann. 1878, vol. i. p. 298, 

 pi. xvii. fig. 1). 



Again, Baron Rosen's representations of S. Ungerni 

 (Taf. ix. figs. 5 & 6) and 8. dentata (Taf. x, figs. 1 & 3), 

 which were similar forms to S. granulata^ Nich., are, in 

 the matter of the conical elevations on the surface still re- 



