a General History of the Marine Polyzoa. 71 



irregular in shape), somewhat produced below the aperture, 

 with a broad strongly crenated border sloping slightly out- 

 wards ; front wall wholly membranous, with the orifice at the 

 very top of it ; an acuminate spine at the bottom of the aper- 

 ture bending inward, and usually two or three on each side. 

 Avicularia distributed over the zoarium in the intercellular 

 spaces, placed near the top of the zooecium at one side ; beak 

 straight, raised, slanting upwards, elongate, with a narrow 

 central channel ; mandible broad at the base, produced above 

 into a slender vibraculoid spine, slightly curved in towards 

 the tip. Ooirium rounded, silvery, frosted. 



Loc. Madeira, on Pinna (J. Y. J.) ; Naples, from just 

 below low- water mark to 40 fathoms (Waters). 



This is undoubtedly the form figured by Mr. Waters, in 

 his catalogue of the Polyzoa of the Bay of Naples, as M. 

 Flemingii. It has, however, no close affinity with that species, 

 but belongs to the same section of the genus as the British 

 M. curvirostriSj mihi, in which there is no trace of a calca- 

 reous lamina in front. The avicularium is a striking feature, 

 with its long slender mandible rising from an expanded sub- 

 triangular base. The spines are variable in number ; but 

 there are usually two on each side, besides the one at the 

 base of the aperture, which is often tall and acuminate. I 

 have met, however, with four on one side and three on the 

 other. The portion of the zocecium which is produced below 

 the aperture is very commonly concealed by the crowding of 

 the cells. 



Membranipora nodulifera, n. sp. (PL IX. fig. 2.) 



Zocecia slender-oval, elongate, wholly membranous in front ; 

 margins thin, set with numerous, small, white nodules. Avi- 

 cularia rather large, elliptical, raised in front, generally 

 placed transversely at the top of each cell on a distinct area ; 

 mandible rounded (?). cerium very small and shallow, a 

 mere hood over the extremity of the cell, smooth, projecting 

 in front into a sharp prominent point. 



Zoarium forming a very regular and delicate network. 



Loc. Madeira (J. Y. J.). 



The nodulated margins constitute the salient characteristic 

 of this very pretty species. 



Membranipora crassimarginata, n. sp. 

 (PI. IX. fig. 1.) 



Zooecia very large and deep, of a regular oval shape, the 

 margin, from the upper rim to the junction with the mem- 

 branous area (forming a broad border), very strongly crenate ; 



