418 CM. Ma'plestone : 



into a prominent umbo. Ooecium oval, raised above the surface 

 of the zoarium, with a triangular opening on the summit. 



The form of the peristome in this species is very various, but 

 the narrow, slit-like notch is always present, though not always 

 in the same position, and the raised umbo is in most cases very 

 much more prominent than shown in the figure, but, as in 

 them, the thyrostome is consequently almost hidden, so the 

 figure was drawn from that portion of the zoarium bearing the 

 only ooecium present on the specimen. 



Mucponella pugata, n. sp. (PI. XXVITT., Fig. 20;. 



Zoarium encrusting. Zooecia elongated ; surface very rugose, 

 covered with irregular, rough elevations. Thyrostome orbicular, 

 with a prominent quadrate mucro in the proximal margin. 

 Occasionally a very large avicularium, with a long, acute man- 

 dible, on one side of the zooecia. pointing horizontally. Mar- 

 ginal zooecia fui'nished with five slender spines on the edge of 

 the thyrostome. Ooecium orbicular, somewhat flattened, with 

 a round umbo in the centre and others round the margin and on 

 the sufrace. 



A very rugose species. With age the spines seen on the 

 marginal zooecia disappear. 



Cellepopa crenulata, n, sp. (PI. XXA^ITI., Fig. Jl). 



Zoarium encrusting. Zooecia orbicular or cylindrical, closely 

 crowded together so that only the upper or distal surface is 

 visilile. This surface is covered with irregularly shaped mamil- 

 lations, mostly radially arranged. Thyrostome orbicular, margin 

 slightly raised and crenate. A few large wedge-shaped avicularia 

 scattered about the zoarium. 



The mandible of the avicularium is wedge-shaped and longi- 

 tudinally ribbed, a very uncommon shape. 



EXPLANATION OF PLATES XXVI.-XXVTTL 



Fig. 1. — Cateuaria iiifuii(lil)ulit"ormis. x 36. 

 ,, 2. — ScrupoceUaiia gilbertensis. x 50. 

 „ 3. — Megapora gilbertensi.s. x 25. ;>;i x 3(). 



