82 Dr. Th. Mortensen oh sovie Echinothurih 



H.^mbnig belonging to the new ^/•opo.soma-speclos and to 

 Asthenosoma ijimai, two specimens of eacli. All these 

 spccinienp, those from Hanibnvg as well as those from 

 the British Museum, were tak^-n by the same collector, 

 Mr. Owsten, in jhe. Sag4\mi Sea at a rlepth of 50 fathoms. 

 Further, I found among a collection of EcUinids sent me for 

 examination by Professor S. F. Harmer, of Cambridge, some 

 s))ecimens of a hitherto unknown species of Phormoaoma, 

 Having learnt from Professor Doderlein that this species is 

 not represented among the collections of the ' Valdivia ' 

 Expedition, I thonglit it desirable to describe it also on 

 this occasion. The specimens were taken (1892) by the 

 'Investigator' in the Bay of Benoal at a depth of G78 

 fathoms. AVith the permission of Piof. A. Alcock, Prof. R. 

 Koehler (who will work out tlie Echinids of the ' Investi- 

 gator'), and Prof. S. F. Harmer, the s|)ecies is described 

 here under the name of Phormosoma verdcilUdnm, sp. n., the 

 name indicating the most prominent feature of the species, 

 viz. the curious verticillated primary aljactinal si)ines. 



The new species of Arceosoma, whicii, according to the 

 wish of Professor Bell, I name A. Oivsteni, in honour of the 

 collector, is especially interesting on account of its primitive 

 " tetradactyle'' pedicellarite. As regards Mr. Yoshiwara's 

 two s|)ecies, one {Aslhenosoma ijifnai) proves really to belong 

 to the genus Ast/ieyiosomd i\s Wm'ited by me in the 'Ingolf* 

 :Echinoidea, the other {Ablhenosoma longisj)lnuiii) to the 

 genus Calveri'o, and it can even scarcely be doubted that it is 

 identical with Calveria gracilis (Agass.). 



1. Arrposoma Oiosteni, sp. n. 

 (PI. II. figs. 1, 2; PL V. figs. 4-9, 11, 18-20.) 



The test is rather flexible, cf the usual low form; the edge 

 is rounded, the actinal side flat. (By filling it with spirit 

 through the anal opening under a moderate pressure the 

 test assumes its natural form ; a specimen of 140 mm. diameter 

 was thus found to be 65 mm. high.) 



The ajjical area is rather small (24 mm. in the specimen 

 of 140 mm. diameter), of the usual Echinothurid type, the 

 genital and ocular plates being widely separated. The 

 genital plates are rather elongate; the genital openings are 

 large, covered by a distinct papilla ; they are situated in 

 the middle of the plate. The madreporic plate is distinctly 

 larger than the other genital plates ; the pores do not spread 

 over the neighbouring plates. The genital and ocular plates, 

 as well as tli^ numerous small anal |jlates, are covered with 

 spines. The inner anal plates not distinctly elongate. 



