70 
TH. MORTENSEN, 
(Schwed. Südpolar-Exp. 
are deepened or not, the main character upon which Philippi distinguished his 
two »species» cavernosus and australis , is only a sexual difference. The rela- 
tive size of the petals differs conspicuously: the posterior petals are as long as 
or even a little longer than the anterior ones in Agassizii, somewhat shorter in 
cavernosus , much shorter in Philippii. The frontal ambulacrum is flush with the 
test in Agassizii , deepened in the other species. A. Philippii has only the an- 
terior paired petals deepened in the female, while the other species have both the 
anterior and the posterior petals deepened. The number of genital pores cannot, 
on the other hand, be used as a certain specific character, two or three pores oc- 
curring equally frequently in A. Philippii (which species was distinguished by LovÉN 
mainly by the supposed character of having only two genital pores); also in typical 
A. cavernosus two genital pores may occur. (Philippi says, in his paper »Über die 
chilenischen Seeigel»: »Ich kenne jetzt noch eine Art, bei welcher auf der linken 
Seite gar kein Eierstock liegt»; probably this will turn out to be an individual ab- 
normality of one of the known species.) — The position of the apical system is gen- 
erally central in all the species, but in some specimens of cavernosus it is distinctly 
posterior, without any other characters distinguishing these specimens from the ty- 
pical form ; they can certainly not even be made a separate variety, all transitional 
forms occurring. Other specimens differ from the typical cavernosus in the unusual 
height of the test; but here likewise transitional forms occur. 
After all I think we may distinguish with certainty the following species of the 
genus Abatus: cavernosus (PlilL.) (with the synonyms australis PlIIL. and gallego- 
sensis De Loriol), Agassizii (PFEFFER), Philippii LovÉN and cordatus (Verrill). 
As for A. elongatus (Koehler) I am much inclined to think that it will prove to 
be identical with A. Agassizii. 
Abatus cavernosus (Phil.). 
PI. IX. PI. X, Figs. 2, 4, 6—8, 10—13. PI- XVII, Fig. 9. PI. XVIII, Figs. 3—4. PI. XIX, Figs. 28—30, 
32—33- 35— 39> 41— 43> 45-46, 5 0 —5i- 
Tripylus cavernosus Philippi. 1845. Beschreibung einiger neuen Echinodermen. Arch. f. Naturgesch. XI. 
I. p. 345. Taf. XI. Fig. 2. 
— australis — - Ibidem, p. 347. Taf. XI. Fig. 3. 
Brissopsis cavernosus L. Agassiz & Desor. 1847. Catalogue raisonné des Échinides. Ann. Sc. nat. 3 ser. 
VIII, p. IS- 
— australis — — Ibidem. 
Tripylus ( Abattis ) cavernosus Troschel. 1851. Über die Gattung Tripylus. Arch. f. Naturgesch. XVII. 
I. p. 72. 
— australis — — Ibidem. 
Faorina cavernosa Gray. 1855. Catalogue of recent Echinida, p. 57. 
— australis — — Ibidem. 
(?) Hemiaster cavernosus A. Agassiz. 1881. »Challenger» Echinoidea p. 177 (pro parte). 
