the Genus Stenopora, Lonsdale. 



183 



Ohs. The type-specimen of S. crinita, LonscL, now in the 

 British Museiim, is a large mass about 4^ inches in length 

 and composed of long basaltiform corallites, which diverge 

 from one another bj the interpolation of new tubes with a 

 very gentle outward inclination. The average diameter of 

 the corallites is about half a millim., and they are polygonal 

 in shape and in close contact throughout. The growth of the 

 corallum was periodic, and the entire mass (as shown in 

 Lonsdale's excellent figure) is stratified, the polygonal coral- 

 lites showing a slight transverse wrinkling as they approach 

 the upper surface of each successive stratum. It seems 

 almost certain, however, that the type-specimen is only tlie 

 central portion of a large corallum of which none of the outer 

 portion is preserved ; and there is therefore no reason to doubt 

 that the corallites in the peripheral region of the corallum 

 would exhibit the characteristic annulations of the genus. 



Fiff. 2. 



Sections of Stenopora crinita, Lonsdale (M'Cormick collection), enlarged 

 twelve times. A. Tangential section, passing in part through the 

 thickened nodes and in part through the unthickened segments of 

 the corallites : a, acanthopores. B. Vertical sectiou, showing the 

 bead-like periodic thickenings of the walls of the tubes and the 

 tabulae. Both sections show a dense brown-coloured irregular 

 lining in all the tubes ; but this seems to be clearly due to minerali- 

 zation, and is omitted in the figure. 



Indeed in other specimens which may be unhesitatingly 

 identified with this species, and in which the external zone of 

 the corallum is preserved, the corallites do actually show the 

 periodic annulations which are found in all the other species 

 of the genus. 



Thin sections of such specimens, taken in the peripheral 



