66 TH. MORTENSEN, (Schwed. Siidpolar-Exp. 



Abatus, as will be shown later on. For the present this form may be left out of con- 

 sideration, as also the ScJiizaster {Brisaster) Moseleyi A. Ag., while there will be 

 reason to discuss the ScJiizaster {Tripylus) Philippii (Gray) together with the other 

 species mentioned above. 



There have thus been established no less than 8 species of the •>-> Hemiaster^ (Aba- 

 ^)-group from South America viz.: Tripylus excavatus Phil., cavernosas Phil., 

 australis Phil., Faorina antarctica Gray, Abatus Philippii LOVEN, Hemiaster Agas- 

 sizii PFEFFER, H. gallegosensis De Lork >L and H. elongatus KOEHLER, which have 

 been regarded as synonyms in different ways, even made one species altogether 

 (except gallegosensis and elongatus, which have evidently only their recent date to 

 thank for not having likewise been made synonyms of cavernosus). To these must 

 be added the Kerguelen-species, cordatus, likewise generally regarded as a synonym 

 of cavernosus. It was then very desirable to have all these forms thoroughly re- 

 examined, and the Swedish South Polar Expedition has given me the occasion to 

 undertake that work. Though the material collected by this Expedition is rather 

 large (the collection of the Swedish Fuegian Expedition 1895 — 97, likewise placed 

 at my disposal, contains only little material of these forms), it would not suffice for 

 a thorough revision of the whole group. I have therefore made every effort to get as 

 much material as possible, and especially to have the type specimens reexamined. 

 Everywhere I met the greatest liberality, for which I may express my deep gratitude. 

 Professor LUDWIG sent me the co-types of PHILIPPl's Tripylus excavatus, australis 

 and cavernosus; Prof. TlIEEL sent me the type of Loven's Abatus Philippii, together 

 with some other specimens identified by LOVEN. From Prof. JOUBIN I have received 

 one of Bernard's specimens, and from Dr. Meissner I received some of the spe- 

 cimens mentioned by him in his paper on the Chilenian Echini. De LORIOL sent 

 me a pair of specimens of his Hemiaster gallegosensis, and from the Hamburg Mu- 

 seum I received the types of Pfeffer's Hemiaster Agassizii together with the whole 

 rich material of South American Spatangoids contained in the collections of this 

 Museum. Further I have examined in the British Museum the type specimens of 

 Gray's Faorina antarctica and the specimens from the »Challenger», and lastly I had 

 the rich material of Abatus cordatus collected at Kerguelen by the German South 

 Polar Expedition. It must be conceded, therefore, that I have done my best to 

 secure a good basis for my researches on this group of Spatangoids. 



We may first examine the value of the genera Tripylus and Abatus. (That the 

 Abatus-species have no nearer relation to Hemiaster, with which genus they have 

 for so long time been associated, I think I have shown definitely in »Die Echinoiden 

 d. deutschen Sudpolar-Expedition» p. 90 — 91, the main differences being 1) that in 

 Abatus the apical system is ethmolytic, with 2 — 3 genital openings, while in Hemi- 

 aster it is ethmophract, with 4 genital openings, and 2) that in Abatus a latero-anal 



