128 THE CRAG POLYZOA. 



Genus 14. ALVEOLARIA, (n. gen.} 



Polyzoario massive globoso ; superficie in areas hexagonas vel polygonas septis longitu- 

 dinaliter sulcatis subdivisft. Cellularum orificiis per totam areaiu distributis. 



Polyzoarium massive, globose ; surface divided into liexa- or polygonal areas by raised 

 lines, which are finely silicate longitudinally. The interior of the area uniformly occupied 

 by the openings of the cells. 



1. A. SEMIOVATA, (. ap.) PI. XIX, fig. 4; PI. XXI, fig. 3 (section). 



Sp. unica. 

 BLUMENBAUHIUM, Sowerby, Kouig Icon., 75, fig. 69. 



Habitat. C. Crag, S. Wood; J. S. B. 



This is one of the most curious and peculiar forms of cyclostomatous Polyzoa met with 

 in the Crag, and apparently confined solely to that formation. In its massive, hemi- 

 spherical form and general aspect, when worn smooth and covered with extraneous 

 matters, it resembles the two species of Fasricularia, with which it is associated, but in its 

 real structure it differs most widely from them, as well as from any hitherto known 

 Polyzoon. 



In PI. XIX, fig. 4 (), a polygonal cup-shaped object, cellular within, and smooth or 

 slightly wrinkled on the exterior, and at (b) in the same figure, the entire upper surface 

 of one, and portions of the same surface of seven other similar cup-shaped growths 

 will be seen in close apposition. They represent, in fact, a number of hexagonal or penta- 

 gonal hollows, separated by raised lines, and, on close inspection, it will be seen that 

 these ridges are not simple, but that each is marked with a fine longitudinal furrow, indi- 

 cating the lines of contact of two contiguous alveoli. The entire growth, in short, is 

 composed of an aggregation of cup-shaped bodies, resembling that figured at (a) ; and in 

 well-preserved specimens, which appear to be very abundantly met with, the real structure 

 may be readily made out, even when they are of very large size ; and besides these, many 

 specimens in an earlier stage of development will be found, showing the process of growth 

 still more satisfactorily. 



