PORINID.E. 



fully stellate character. Calcification is carried to a great 

 extent in this species ; and the walls become very thick and 

 solid, and rather coarse in appearance, as we might ex- 

 pect in a deep-water form. It is often difficult to deter- 

 mine the nature of the pore on the front of the neck-like 

 prolongation of the cell. In the older zooecia it is usually 

 a simple circular opening of rather large size ; but in the 

 younger it shows its true character, and is covered by a 

 pointed avicularium. The smaller pore on the upper 

 margin, which is sometimes very conspicuous, is also avicu- 

 larian ; but the appendage itself is very generally wanting ; 

 when present, its mandible is directed downwards. 



There is considerable variability in the shape of the 

 orifice, which seems to be chiefly due to the thickening of 

 the peristome with age. 



HABITAT. On stones, shells, Gorgonia, &c., from deep 

 water. 



LOCALITY. Shetland, on shell (Barlee) : ibid., common 

 in 80-170 fathoms (A. M. N.). 



GEOGRAPHICAL DISTRIBUTION. North Sea, off Norway, 

 on Gorgonia and stones from 200-300 fathoms (Baron 

 Uggla) : W. off Tortugas (Pourtales) . 



In A. monodon the zooecia are distinct, but separated by 

 shallow sutures, and very slightly convex, so that the 

 zoarium has a flattish appearance. The stellate character 

 of the punctures with which they are thickly covered, is 

 hardly apparent except in young specimens. The oral ex- 

 tremity is slightly turned upwards ; and the mouth is girt 

 about with a massive peristome : the pore in the centre of 

 the upper margin is the "tooth" which suggested the spe- 

 cific name. 



At the base of the cells there is a row of circular 

 openings. 



