8CHIZOPORELLA ARMATA. 259 



directed outwards, often replaced by a large spatu- 

 late avicularium. Ocecia semicircular, rather shallow, 

 flattened in front ; surface smooth, with obscure radi- 

 ating ridges. 

 Colonies forming large brownish or grey patches. 



HABITAT. On stones, &c., from deep water. 



LOCALITY. South-west of Polperro, in 30 fathoms (T. H.). 



GEOGRAPHICAL DISTRIBUTION. Algiers, on shell (J. 

 Y. J.). 



The cells in this strongly marked species are moderately 

 convex, well denned, arranged very regularly in quincunx, 

 and coarsely granulated. The orifice is rather large, and 

 appears to be deeply depressed from the elevation of the 

 cell- wall around it; it is filled in by a light horn-coloured 

 operculum, which bears a very close resemblance in form 

 to a balloon. In fresh specimens the spines are a very 

 conspicuous feature; they are stout, and of remarkable 

 length. The two foremost are articulated to a short, 

 tubular process; and when the ovicell is present, they 

 stand erect in front of it, and rise high above it. There 

 is sometimes an avicularium on each side of the orifice, 

 sometimes on one side only. The semicircular mandible 

 is turned outwards ; it is interesting to note that on the 

 lower margin of the avicularian aperture there is a minute 

 sinus corresponding to the larger one on the mouth of 

 the cell. The small avicularia are placed at the upper 

 extremity of an ascending process ; occasionally they are 

 situated rather below the inferior margin ; but their more 

 usual position is near the top of the cell. Not unfre- 

 quently their place is occupied by a very different struc- 

 ture. Instead of the small rounded form, there often 

 occurs an elongate avicularium of large size, with a spa- 

 tulatc mandible, usually, but not universally, pointing 



s 2 



