2 TH. MORTEXSEN, (Schwed. Südpolar-Exp. 



The species represented in the collection of the South Polar Expedition are the 

 following, those marked with an * being also represented in the collection of the 

 Fuegian Expedition: 



Ctenocidaris speciosa n. g. n. sp. (South Georgia, Shag Rocks Bank, Graham Region). 

 *Austrocidaris canaliculata (A. Ac.) (Falkland Isl.). 



— spinulosa n. sp. » » 



* Afbacia Dufresnii (Blv.) (Coast of North Argentina). 



* Notecliinus inagellanicits (PiilL.) (Coast of North Argentina, Tierra del Fuego, Falk- 

 land Isl., Graham Region). 

 Stereclnnits Nenuiayeri (MeisSN.) (South Georgia, Graham Region). 



— Agassizii nom. nov. (for ■ainargaritaceus«) (P'alkland Isl., South Georgia, 



Shag Rocks Bank, Burdwood Bank). 

 * Loxechiniis albus (MOL.) (Tierra del Fuego). 

 Plexecliinus Nordenskjoldi MrtsN (Shag Rocks Bank). 

 *Abatus cavernosus (Phil.), with the variety bidens, n. var. (South Georgia). 



— Agassicn (Pfeffer) (South Georgia). 

 *Schizaster {Tripylastcr) Philippii (Gray) (Coast of North Argentina). 

 Amphipneustcs Lorioli KOEHLER (Graham Region). 



— Koelilcri Mrtsn (South Georgia, Shag Rocks Bank). 



The collection thus contains in all 14 species, 4 of which are new, viz. Cteno- 

 cidaris speciosa, Austrocidaris spinulosa, Plexecliinus Nordenskjoldi and Amphi- 

 pneustes Koelilcri; of the two latter there has already been published a preliminary 

 description. * The first of them also represents a new generic type. A new variety, 

 bidens, had to be established for a form of Abatus cavernosus. The stud)- of Arba- 

 cia Dufresnii revealed the fact that a quite different species has hitherto been con- 

 founded with it; this species is described here under the name of y:!ri^rt<"/rt crassispina 

 n. sp. 



Among the more interesting points mentioned in the present work I may name 

 the discovery, that Aniphipneiistes Koehleri shelters its brood, quite similar to 

 what is known in Abatus cavernosus; the description of the development of Abatus 

 cavernosus, from the formation of the apical plates until it has reached maturity, 

 the discovery of a distinct genital plate 5 being of special importance; further the 

 discovery of the remarkable Phyto-Parasite, Echinophyces mirabilis, described from 

 Rhynckocidaris triplopora Mrt.SN in the »Echinoiden der deutschen Südpolar- 

 Expedition», in Ctenocidaris speciosa, where it produces analogous effects, the genital 

 openings being transferred to the middle of the corresponding interambulacra. 



* Th. Mortensex. Some new species of Echinoidea. Vid. Medd. Naturh. Foren. Kobenliavn 1905. 



