108 Descriptions of Keiv, 



hollowed, entire, thin ; in older with a loop-shaped notch, at 

 the angle of which is an avicularium. This notch is fre- 

 quently bridged over, leaving a small foramen, which also 

 is sometimes obliterated, In the latter case the lip is 

 thickened, and at its junction with the lateral margins 

 projects slightly, giving origin to slender, jointed spines ; in 

 many of the older cells the spines are very thick and tele- 

 scopic in appearance, and are frequently confined to one side. 

 The avicularia are very varied, semicircular, spatulate, and 

 pointed ; and there is frequently a semicircular one above a 

 fenestra, and also often one with a long, narrow mandible 

 closing in a bidentate rostrum, opening horizontally inwards 

 on the edge of a fenestra. Ovicell prominent ; the vertical 

 band ending in the base of a sharp, smooth, umbonate pro- 

 cess. Back strongly vibicate, with numerous small,. round 

 avicularia, especially about the edges of the fenestra. 



A small form distinguished by the .much-raised margins 

 of the younger cells and the peculiar umbonate process on the 

 ovicell. These characters are usually so marked that they 

 might seem sufficient to constitute a new species. In some 

 cases, however, the umbonate process scarcely exists, and the 

 vertical band is little more prominent than in sinuata. 

 Young cells of mwnita also not uncommonly have the edges 

 considerably raised. 



R. monilifeva, form munita. 



Polyzoary expanded, foliaceous, convoluted to form large 

 cavernous or calyculate masses. Cells separated by narrow 

 raised lines, surface granular. Peristome expanded forwards 

 with a loop-shaped mark in the centre of the lower lip, 

 closed or perforated below, on one side of which is an avicula- 

 rium. Small oval avicularia on the front of the cells, and 

 various others scattered in different parts. A very large 

 avicularium, with either a semicircular or very long 

 triangular, pointed mandible, above the upper angle of most 

 of the fenestras. Ovicells with the beaded line narrow. 

 Back granular, vibices well-marked, elliptical avicularia 

 more, abundant about the edges of the fenestras. 



Mr. Hincks, in his valuable paper on Retepora, has already 

 proposed the varietal name of munita for this form. The 

 largest specimen I have is 2| by 3 inches, but as all my 

 other specimens are incomplete, I have no doubt it attains a 



