DIASTOPORA SUBORBICULAKIs. 



DIASTOPORA OBELI v (part.), Johnst. B. Z. ed. 2, 270 (probably). 



? DIASTOPOIIA FLABBLLUU, Rciiss, Pol. Wien. Tortiarb. 51, pi. vii. fig. 9*. 



Zoarium thin, closely adnate, usually forming a suborbi- 

 cular or elliptical crust. Zooecia quincuncially arranged, 

 very slender, thickly punctate, separated by distinct 

 lines, upper surface flat, immersed, except at the extre- 

 mity, which is rather abruptly bent upwards, the free 

 portion usually short. Ocecia somewhat ovate, with a 

 tube projecting at the top, speckled, disposed rather 

 regularly at intervals round the zoarium, in successive 

 series. 



Fine specimens are about ^ inch in diameter. 



A LEANING characteristic of this species is the very defi- 

 nite and usually more or less orbicular shape of the zoarium. 

 The number and regular arrangement of the ooecia, which 

 are generally present, are also points that strike the eye 

 at once. Morphologically these are modified cells, and 

 form more or less ovate receptacles, with a tubular orifice. 

 The crust is very thin and closely and entirely adherent, 

 and without any extension of the lamina round it. 



The zoojcia are elongate, slender, dotted over with 

 white points, the surface flat, immersed almost throughout, 

 but usually with the extremity erect and free. This cha- 

 racter is always a very variable one. In the present species 

 the tendency seems to be towards a more complete immer- 

 sion of the cell than is usual ; but in sheltered situations 

 the free portion is often of considerable length. The 

 boundary lines are conspicuous. 



Busk describes the zoarium as either " orbicular or ir- 

 regular/' but in all the specimens I have seen (and the 

 species is abundant on the South-Devon coast), the shape 



* Manzoni considers that this is probably identical with the present spe- 

 cies. Busk, however, regards the identification as too doubtful to justify the 

 adoption of Reuss's name. 



2 ii 



