88 THE VOYAGE OF H.M.S. CHALLENGER. 
Genus 11. Ulophyllia, Milne-Edwards and Haime. 
Ulophyllia, Milne-Edwards and Haime, Cor., ii. p. 377. 
The genus Ulophyllia is distinguished from Isophyllia by the nature of the walls 
and septa. The walls are always thin, more especially at their upper portion, where 
they are often broken through. The septa, though prominent about the centre of the 
calicles, where they generally give rise to a more or less distinct, paliform lobe, are very 
narrow on the upper part of the wall, and often take the form of thickened striations, and 
on this part of the septa the teeth are reduced to very fine serrations or are quite absent. 
The ridges which are thus formed are very narrow and sharp at their upper part, and 
differ altogether from those formed by the thickened wall and prominent septa of 
Tsophyllia. 
The genus is very closely allied to Tridacophyllia, but is distinguished by the greater 
thickness and the less elevation of its walls, by the much greater distinctness and pro- 
minence of its septa, and by the fact that the calicinal centres are confined to the valleys, 
and are not found also on the basal parts of the high ridges as in Tridacophyllia. 
Two species of the genus were collected. 
1. Ulophyllia aspera, n. sp. (Pl. IIL figs. 5-5b). 
Corallum convex or flattened, covered up to the edge bya very thin epitheca, beneath 
which the finely denticulate coste are very distinctly seen. Calicles very frequently 
isolated, but often arranged in small series, which very rarely have as many as five or six 
centres; the single calicles are from 15 to 25 mm. wide in their long diameter, oval, 
elongated or irregular; the calicles in series are separated from each other by large and 
strong septa, which meet from opposite sides of the valley, and are bordered by wide 
interseptal spaces. The width of the series is from 11 to 15 mm., and the depth from 
8 to 12 mm. The walls are thin above and often broken through, with a very ragged 
appearance due to the projection of opposite septa above, thick and very strong below. 
The septa are of five cycles, the last cycle being incomplete in many orders, closely placed 
and unequal, often quite thin, especially in the shallower calicles, prominent below so as to 
form a broad, denticulate, paliform lobe, and rather prominent above with fine, unequal, 
and strong teeth. There are about eight septa to the centimetre along the series, but 
on the outer part of the corallum they are more numerous, often as many as fourteen. 
Columella very abundantly developed, of open trabeculate or closely interlaced tissue. 
Endotheea slight, seldom forming vesicular ridges ; and then but very slightly developed 
and irregularly placed. 
A large specimen of this species, about 16 cm. in diameter, was obtained. Owing to 
