235 
to H. philippinensis only in thickness of the corallum, the structure 
of the septa and the costae is alike in these forms. 
Halomitra echinata (Dana) 
(PI. X, ligs. 123-125, PI. XI, ligs. 134 and 135). 
Zoopilus echinata Dana 1846. 
Locality: D. Exp. t. Kei I si.: Banda, 0—2 m, several fragments, belon- 
ging to at least 3 ex. 
The description of Zoopilus echinatus by Dana is rather short 
and the figures of this form published by the same author are 
altogether insufficient. In one specimen of this species in the U. 
S. National Museum in Washington (probably the type-specimen) 
the central calicle is still to be found, all the other specimens 
which I have seen are regenerated from a small fragment. As the 
species is very incompletely known I give here a new description, 
based on the specimens in my material, the specimen in the U. 
S. Nat. Mus., and those in the Mus. of Comp. Zool. in Cambridge 
(Mass.). The material of this species in the latter museum consists 
of three specimens: one regenerated colony from Fiji, collected by 
the U. S. Exploring Exp., and two regenerated colonies from Fiji, 
collected by A. Agassiz in 1897. 
Corallum very thin (5—12 mm) and fragile, convex above and 
concave below. Theca very strongly perforated, often with long slits 
(up to 5 mm) in rows between the septa and costae. Chief septa 
alternating with 2—5 septa of lesser prominence. These latter are 
much thinner than the chief septa and are strongly granulated and 
irregularly dentated. The chief septa possess long blunt dentations 
of which 3 — 6 are found in a Space of 10 mm, they are minutely 
granulated and the apex is often divided into secondary dentations. 
With the exception of those in the central region of the specimen 
in the U, S. National Museum hardly any of the chief septa are 
divided into parts by the formation of the (secondary) calicles, for 
the greater part they are found uninterrupted from the central area 
till the margin. The central calicle (fig. 135) is large, shallow, with 
radial arrangement of the septa. It is surrounded by a number of 
somewhat smaller secondary calicles in the centre of which the 
large septa are broken. These calicles have the same general 
appearance as those in H. philippinensis. In the remaining part of 
