176 MICROPORID.E. 



does occur_, however, occasionally, though never such a 

 striking feature as it is represented in Manzoni^s figure. 



The mouth has an obscurely trifoliate appearance, which 

 is due to a slight marginal projection on each side, almost 

 immediately above the lower lip. This constitutes an 

 important difference between the present species and 

 M. coriacea. Another is found in the thickened border, 

 more or less pointed above, surrounding the upper margin 

 of the orifice. The area is also much more thickly punct- 

 ured than in M. coriacea ; and the punctures are of larger 

 size. 



Genus STEGANOPORELLA, Smitt. 



Der. Dim. of Stegaiwpora ((rreyavos, covered, and Tropos, an opening), 



a genus of Polyzoa. 



Membranipora (part.), auctt. 

 Reptescharellina (part.), D'Orbigny, 

 Steginoporella, Smitt, Flor. Bryoz. 



Generic Character. — Zoarium incrusting or {occasion- 

 ally) rising into foliaceous expansions *. Zocecia with the 

 external characters of Micropora, but having an inner 

 chamber occupying the whole of the cavity below, and above 

 narrowed into a tubular passage, which either communicates 

 directly ivith the orifice or opens into a second chamber im- 

 mediately beneath it. 



The species in which the characters of this group are 

 most strikingly exhibited is the Membranipora magnilabris, 

 Busk. In some respects, however, it is peculiar; and we 

 have a better average representative of the genus in our 

 British species. 



* According to Smitt, iS'. magnilabris, Busk, sometimes assumes this con- 

 dition (Flor. Bryoz. pt. ii. pi. iv. fig. 100). 



