Structure of Stromatopora. 263 



and thus in Labechia we have a transitional form from 

 Favosites gothlandicus to the rectilinear structure of Stroma- 

 topora, which, in the horizontal section (fig. 2, a, and fig. 8, a) , 

 it closely resembles — accounting for Lindstrom's statement 

 that G. Eisen had pointed out to him " that there are spe- 

 cimens found in Gothland combining the peculiar features 

 of Labechia with those of Ca?nostroma" = Stromatopora 

 (Ann. 1876, vol. xviii. p. 5). 



That Labechia was a species of Hydractinia is evident from 

 its structure and mode of growth — i.e. more or less laminiform, 

 enveloping small shells and corals in its course of increase. I 

 make this statement from two large specimens now before me, 

 in which there are a number of layers of Labechia varying in 

 thickness under one third of an inch, heaped irregularly upon 

 each other with shells, corals, and sand between them, some 

 of the former of which have not only become united to and 

 imbedded in the layers, but also, after the manner of Iiydrac- 

 ti?iia, appear to have become partly absorbed into their struc- 

 ture ; so that, under this form, Labechia, contrary to Messrs. 

 Nicholson and Murie's statement (Journ. Linn. Soc. vol. xiv. 

 p. 235), is closely allied to Hydractinia, which seems to show 

 that the assertion was made upon a single specimen in which 

 this did not occur. 



There is a species of Stromatopora, viz. S. elegans, Rosen 

 (the well-known " staghorn variety"), among those in the 

 possession of the lapidaries hereabouts, which in the pre- 

 sence and position of the stellate venation has puzzled both 

 Mr. Champernowne and myself; for the pattern in the ccenen- 

 chyma exactly represents the stellate venation in the hori- 

 zontal section, but in its branches will be found to end not 

 like that of the usual venation, namely in the ccenosarcal 

 cavities, but in the fibre of the coenenchyma itself; and yet 

 the branches of the stellate venation, when it happens by 

 the section to have come into view, follow the course of the 

 coenenchymal stellation. The stellate figure in the coenen- 

 chyma (however much, in the horizontal section, it may 

 look like the cylindrical branches of the stellate venation) 

 has a vertical extension, as well as a horizontal one, in the 

 coenenchyma, so that the horizontal section might cut off seve- 

 ral thin slices and still leave the same figure ; while the 

 stellate venation is probably confined to only one part of it, 

 and therefore only now and then, in small fragments, is seen, 

 but, of course, must somewhere become continuous with 

 the ccenosarcal cavities. Hence I should be inclined to infer 

 that the "stellate venation " maintains its horizontal position, 

 however much vertically the stellate figure assumed by the 



