MEMBRANIPORA CORNIGERA. 165 



Zooecia pyriform, or somewhat lozenge-shaped; lamina 

 minutely granular^ filling in more than half the area ; 

 margin not beaded^ armed with six spines, of which two 

 are placed at the top of the cell and the rest on the 

 sides, the lowest pair forked. Large oblong avicularia, 

 with a rounded mandible, distributed amongst the cells. 

 Ooecia rounded, finely granular. 



Habitat. On stones, coral, &c., from deep water. 



Locality. Shetland (Barlee) : " a very interesting and 

 very rare species ;" 100 fathoms. Outer Haaf (A. M. N.) . 



Geographical Distribution. On Ocul'ma from 200- 

 300 fathoms, off the coast of Norw^ay (Baron Uggla) . 



This species is readily distinguished by the two forked 

 spines bending inwards over the lower part of the aper- 

 ture, and by the character of its avicularia, which are of 

 the Flustrine type, and have a semicircular mandible, 

 a form which occurs on only one other British species, 

 M. flustroides. They are numerous, and are distributed 

 amongst the cells, and on the same plane Avith them, 

 instead of being developed upon them as secondary for- 

 mations. 



In old and worn specimens, from which all the mem- 

 branous portions have been removed, a curious appearance 

 is presented by the upper part of the aperture, which is 

 marked off by a calcareous rib, and divided into two 

 compartments (Plate XXII. fig. 3). This peculiarity is 

 usually concealed by the oral valve; but when visible, it 

 changes materially the aspect of the species. 



