84 TH. MORTENSEN, (Schwed. Südpolar-Exp. 



Luven 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 •^Heniias1er>> aiistralis Ag.\SS1Z 

 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 anstra/is is 

 only the young of cavernosus. — Later on, in the Challenger» Echinoidea Ag.\SSIZ 

 is of opinion that A. Pliilippii is only a synon)-m of cavernosus. 



Through the kindness of Professor Theei, I have had occasion to examine the 

 type specimens of LuvËN and to compare them direct]}- with my specimens; like- 

 wise Prof. Theel sent me some specimens identified by LtjVÉX 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. 

 Pliilippii, the latter A. cavernosus. Though LovÉX himself has thus not had the 

 right conception of liis species A. Pliilippii, 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 ma\- be added 

 the characters pointed out by Agassiz. It must, however, be conceded that quite 

 reliable characters by which to distinguish the males of Pliilippii and cavernosus 

 can scarcely be pointed out, so that it may sometimes be verj- difficult to decide 

 whether some specimen is cavernosus or Pliilippii. (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. Pliilippii to be onl\- a variety of rrtZ'^r- 

 nosiis — 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 



