144 THE VOYAGE OF H.M.S. CHALLENGER. 
to the much less porous condition of the wall. With Halomitra it agrees in the nature 
of the septal teeth, and in the size and distinctness of the parent calicle; but it is easily 
distinguished by the costal rays, which are fine and do not form strong and thick lamellae 
with coarse spines, by its manner of growth with high septal cycles on the long axis, by 
the development of few smaller calicles in the longitudinal axis, and by the reduced wall. 
From Zoopilus, to which it seems to be more closely related, it is distinguished by the 
possession of a distinct, large, central calicle, by the development of fresh calicles in the 
course of the long axis close to the parent calicle and interrupting the larger as well as 
the smaller septa, and by the costa, which are fine and not prominent nor divided into 
strong clustered teeth. In the specimen of Zoopilus figured by Dana, there is a distinct 
central depression, but this is stated by him to be an “accidental distortion and not the 
position of a medial orireme.” In the absence of such a central calicle, the nature of the 
long, large, radiating, uninterrupted septa remains incomprehensible. 
Sandalolitha dentata, Quelch (Pl. VII. figs. 1-1d). 
Sandalolitha dentata, Quelch, Ann. and Mag. Nat. Hist., vol. xiii, 1884, p. 295. 
Corallum almost flat, irregularly sandal-shaped, fragile, translucent, being about 
6 mm. thick, except immediately around the mouth of the central calicle where the 
septa are somewhat elevated and thickened. The parent calicle attains a large size, 
nearly 15 cm. in length, before the smaller calicles are developed. Wall very thin, 
pierced with numerous small pores ; cost slightly unequal, with very small, granulated, 
blunt spines, distinct, curving in radiating lines towards the short axis of the corallum 
except at the centre, where the costal spines become crowded over a thickened circular 
space that seems to have been a former base of attachment. Septa of the central 
calicle of seven complete cycles, but incomplete orders are developed at the extremities 
of the long axis of as many as sixteen cycles; those of the first three cycles subequal, 
slightly thickened and prominent at the centre; and, with the exception of the very 
small ones, all the septa are nearly equally raised over the general surface, cut into 
strong, long, and narrow teeth, very granulated, especially at the apex of the teeth ; the 
teeth are obtuse or pointed, the extremity being subdivided into pointed spinules. The 
septa of the higher orders unite, one on each side, with one of a lower order at that 
part of it from which they originate. Columella rudimentary. 
Only a single specimen of this species was obtained. It is rather bent to one side, 
about 15 em. long. and 6°5 cm. wide, narrowing slightly towards the extremities and 
rounding off suddenly. At the centre, where the septa are raised, it is about 15 mm. 
thick, and, except at this thickened portion, the corallum is quite translucent. The 
under portion is marked with many concentric, curved undulations, elongated in the 
direction of the long axis, following the growth of the corallum. In one direction of its 
