86 
TH. MORTENSEN, 
(Schwed. Südpolar-Exp. 
Abatus Agassizii (Pfeffer). 
PL X, Figs. I, 3, 5, 9, 14. PI. XIX, Fig. 40. 
Hemiaster cavernosus A. Agassiz. 1872. Revision of Echini, p. 587. PL XXI. c. figs. 1 — 2. 
— australis — — — — • 586. — — 3. 
— cavernosus G. Pfeffer. 1889. Zur Fauna von Süd-Georgien. Jahrb. d. Hamb. wiss. Anst. VI. 
p. 49. 
— Agassizii Pfeffer. M. S. 
— cavernosus Meissner. 1900. Ecliinoidea d. Hamb. Magalh. Sammelreise, p. 13 — 14. 
? — elongatus Koehler. 1908. Astéries, Ophiures et Échinides de l’Expéd. antarct. nat. Écoss. 
Trans. R. Soc. Edinb. XLVI, p. 618. PL XVI, figs. 145 — 15S. 
This species differs in some respects markedly from cavernosus and Pliilippii, 
and it seems scarcely doubtful that it is a distinct species; in any case it must be 
kept separate from cavernosus or Philippii , even if it may ultimately prove that it 
deserves only to rank as a variety of cavernosus. — It seems highly probable that 
it was this species which AGASSIZ described and figured under the name of Hemi- 
aster cavernosus and australis in the »Revision of Echini»; the photographic figures 
given there agree very closely with the typical A. Agassizii, as will be seen on 
comparing them with the figures given here. (On account of this De LORIOT, on 
having the true cavernosus before him and seeing that it differed from H. cavernosus 
of the »Revision», described it as a new species, H. gallegosensis.) It further seems 
not improbable that the H. elongatus recently described by KOEHLER (Op. cit.) is 
identical with this species. Unfortunately the otherwise very elaborate description 
does not give any information of the subanal tubefeet; a communcaition from my side 
to the Scottish Oceanographical Laboratory in Edinburgh, where the material is pre- 
served, has not been answered, so that I am unable to give information on the point 
in question, and I must therefore leave it undecided, whether elongatus is identical 
with Agassizii or a separate species. 
The shape of the test (PI. X. Figs. 5, 9) is upon the whole like that of cordatus 
(cf. PI. XVIII. Figs. 2, 4, 16, 20 of »Die Echinoiden d. deutschen Südpolar-Exped.), 
it only affords one marked distinguishing feature, viz. in the odd anterior ambulacrum 
being flush with the. test at the front end. On the abactinal side, inside the fasciole, 
it is slightly sunken. The posterior petals are as long as, or even longer than, the 
anterior ones; only in one specimen (from Stat. 33) I find the posterior petals 
slightly shorter than the anterior; the latter are directed more sidewards than is 
generally the case in cavernosus. The apical system is central, as is also the vertex, 
the test sloping from here towards both ends. The subanal tubefeet are rudimentary 
as in cordatus , only in the specimen from Stat. 33 one tubefoot is developed on 
one side. The peristome is somewhat larger than in the other species, sometimes 
even very large. Along the border of the labrum small spines and rather numerous 
