a General History of the Marine. Vulyzoa. 91 



dinal series, closely united ; area broad-ovate, occupying 

 usually about three quarters of the front of the cell, the lower 

 half filled in by a minutely granular lamina, which slopes 

 steeply up to the top of the inferior portion of the cell • aper- 

 ture occupying the upper half, somewhat semicircular, with a 

 membranous covering, margin thin and smooth, sometimes of 

 a brown colour ; in one corner of the aperture, between the 

 wall of the cell and the lamina, a small horn-shaped tube, 

 opening out below by a wide mouth into the cavity of the 

 cell, and tapering off towards its upper extremity; the portion 

 of the cell below the area elevated, bearing several (one to 

 five) prominent polished nodules, wall smooth and glossy. 

 Avicularia none. Oaicia (?). 



The principal variation to which this extremely interesting 

 form seems to be liable is in the number of the nodular pro- 

 cesses. Occasionally the produced lower portion of the cell 

 is altogether obliterated, and the area extends to the top of 

 the neighbouring zooecium. In such cases a single nodule 

 occurs on the line of junction, or sometimes two. But usually 

 there is a considerable space below the area, which is crowded 

 with the glossy tubercles ; they are sometimes separated by 

 delicate raised white lines. The zooecia are deep ; and the 

 cell- wall seems to rise a good deal above the level of the 

 membranous covering of the aperture. The zoarium has a 

 bright and shining appearance. 



EXPLANATION OF THE PLATES. 



Plate IX. 



Fig. 1. Membranipora crassimarginata, n. sp. 1 a, elongated avieularian 



cell and ocecium. 



Fig. 2. Membranipora nodidifera, n. sp. 



Fig. 3. Membranipora t&nuirostris, n. sp. 



Fig. 4. Membranipora granvlifera, n. sp. 



Fig. 5. Setosclla oulnerata, Busk (Madeira). 



Fig. G. Smittia marmorea, Hincks. 



Fig. 7. Lepralia Kirchenpaueri, Heller, var. 7 a. Ocecium. 



Tlate X. 



Fig. 1. Cribrilina radiata, var. 



Fig. 2. Porella nitidissima, n. sp. 



Fig. 3. Lepralia Pallasiana, with ocecia. 



Fig. 4. PhylacteUa lucida, n. sp. 



Fig. 5. Membranipora albida, n. sp. 



Fig. 0. Membranipora horrida, n. sp. 



Fig. 7. Membranipora distorta, n. sp. 



Fig. 8. Membranipora villvsa, n. sp. 



Fig. 9. Membranipora mamillaris. Lamx., with avicularium. 



