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GENUS II. PEACHIA (Gosse). 



Siphonactinia (Dan. et Kob.). 



Column cylindrical, pear-shaped, or swelling in the 

 middle, rounded at the posterior extremity, where 

 there is an orifice ; margin entire, forming an indis- 

 tinct parapet. Surface smooth, without loopholes, 

 but studded in every part with very minute and very 

 numerous suckers. 



Disk flat, or very slightly conical, smooth. 



Tentacles of one kind, twelve, thick, short, obtusely 

 pointed ; marginal ; imperfectly retractile. 



Mouth not elevated on a cone ; lip thin, abrupt, pro- 

 trusile, sometimes lobed. A single gonidial groove, 

 the edges of which are soldered together so as to 

 form a tube, which terminates above in a thickened, 

 expanded rim {conchula), the margin of which is more 

 or less divided. 



Acontia wanting. 



ANALYSIS OF BRITISH SPECIES. 



Column lengthened. 



Conchula with from 12 to 20 lobes hastata. 



Conchula with 3 ovate lobes triphylia. 



Column short. 



Conchula with 5 shallow lobes imdata. 



