8 4 
TH. MORTENSEN, 
(Schwed. Südpolar-Exp. 
LovëN never gave a description of this species, the main character of which 
he found in the two genital pores. This character, however, is shown by AGASSIZ 
(»Hassler» Echini) to be unreliable, two or three genital pores occurring quite in- 
differently. As characters distinguishing the species from » Hemiaster » australis AGASSIZ 
points out, the »short posterior lateral ambulacral petals and its narrow peripetalous 
fasciole». Otherwise the males, on account of their shallow ambulacra, are taken to 
be only the younger stages, and the suggestion is made that likewise australis is 
only the young of cavernosus. — Later on, in the »Challenger» Echinoidea AGASSIZ 
is of opinion that A. Philippii is only a synonym of cavernosus. 
Through the kindness of Professor ThÉEL I have had occasion to examine the 
type specimens of LovÉN and to compare them directly with my specimens; like- 
wise Prof. Theel sent me some specimens identified by LovÉN as A. cavernosus. 
It was evident enough that the only distinction between these specimens was that 
some of them have 2, others three genital pores; the former had been named A. 
Philippii , the latter A. cavernosus. Though LovÉN himself has thus not had the 
right conception of his species A. Philippii , it seems to me that it is real enough, 
its main character being not the number of the genital pores, but the feature that 
only the anterior paired petals are deepened in the female , to which may be added 
the characters pointed out by AGASSIZ. It must, however, be conceded that quite 
reliable characters by which to distinguish the males of Philippii and cavernosus 
can scarcely be pointed out, so that it may sometimes be very difficult to decide 
whether some specimen is cavernosus or Philippii. (Perhaps such specimens may 
be hybrids.) In spite of this uncertainty regarding the males I think it right, on 
account of the very marked features of the females, to keep them as separate spe- 
cies; perhaps a larger material will prove A. Philippii to be only a variety of caver- 
nosus — this, however, is of small importance. That it ought in any case to be 
kept as a separate type seems to me evident. — It may be thus described. 
The test is generally rather flat and broad, the greatest width being at or a 
little before the middle; it narrows somewhat abruptly towards the posterior end. 
The posterior interambulacrum is generally somewhat keeled on the abactinal side, 
the highest point being somewhat behind the apical system, which is central or 
subcentral. The hind end of the test is a little prominent above, slightly concave 
below, whereas in cavernosus it is vertical. The petals of the female are sufficiently 
characterized by the peculiar feature, pointed out above, of only the anterior ones 
being deepened; the posterior ones are somewhat shorter. In the males they are 
comparatively a little longer than in cavernosus; the anterior ones are directed some- 
what more sidewards, the posterior generally somewhat more backwards, the inter- 
ambulacrum between them being slightly narrower than in cavernosus ; it seems to 
be characteristic that the posterior petals are generally somewhat narrower than the 
