MARINE POLYZOA. 35 



Gemellaria loriculata, Savig. Egypt. Polyp. ; Van Beneden, Re- 

 cherch. 33. pi. 5. f. 1 ; Johnst. Hist. Brit. Zooph. ed. 2. 293. 

 t. 47. f. 12, 13, 477; Gray, List Brit. Rad. 134. 



Hab. European Seas. 



2. DIDYMIA. 



Cells joined side to side. Aperture large, oval, wholly ante- 

 rior. Cells all facing the same way. At a bifurcation each cell 

 of the primary pair giving off a secondary pair at the summit. 



Didymia, Busk, Voy. of Rattlesn. i. 3S3. 



1. DIDYMIA SIMPLEX. PL XXXIX. 

 The only species. 



Didymia simplex, Busk, op. cit. 383, t. 1. f. 6. 

 Hob. Bass' Strait, 45 fathoms. 



A fine species, growing in loosely branched tufts to a height of 

 several inches. In some (dried) specimens the branches are 

 slightly incurved, but not in all. The situation of the ovicell is 

 peculiar. It is contained within the upper part of a cell placed 

 between, or rather in front of the pair from which the two 

 branches at a bifurcation take their origin. The ovicelligerous 

 cell differs widely in form from the others, being pyriform and 

 much attenuated below; and the orifice is below the middle. 

 The upper compartment, in which the ovicell itself is lodged, 

 appears to be separated from the lower by a transverse diaphragm. 



3. DIMETOPIA. 



Cells joined back to back. Aperture oblique ; each pair look- 

 ing in a direction at right angles with that of the next. At a bi- 

 furcation the pair being disjoined, each of the disjoined cells 

 gives off a secondary pair. 



Dimetopia, Busk, Voy. of Rattlesn. i. 384. 



1. DIMETOPIA SPICATA. PI. XXIX. fig. 1. 



Cells infundibuliform. Margin thickened, with numerous 

 equidistant, elongated, acute spines. 



Dimetopia spicata, Busk, op. cit. 384. 1. 1. f. 9. 



Hab. Bass' Strait, 45 fathoms ; New Zealand, Lyall, fyc. 



White and transparent, forming thick tufts about 1| to 3 inches 

 or more in height. 



2. DIMETOPIA CORNUTA. PL XXIX. figs. 2, 3. 



Cells contracted below the middle. Aperture oblique, wide 



