82 Dr. Th. Movtensen on some Echinothurids 



Hamburg belonoing to the new ^/wosoma-species and to 

 Asthenosoma ijirnai, two specimens of each. All these 

 specimens, those from ITambnrg as well as tliosc from 

 the Biitis'.i ]\luspum, were token by tlie same collector, 

 ]\lr. Owston, in the Sagami Sea at. a rlepth of 50 fathom?. 

 Further, I fonnf]-amon_o- a collection of Eclijnids sent me for 

 examination by Professor S. F. Ilarmer, of Catnbrida-o, some 

 specimens of a iiitlierto unknown species of Phormo<ioinn. 

 Having" learnt from Professor DoJei'lein that tliis species is 

 not represented among- the colh'ctions of the ' Valdivia ' 

 Expedition, I thnnglit it desirable to describe it also on 

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

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

 fathoms. With the permission of Prof. A. Alcock, Prof. B,. 

 Koehler (who will work out the Ecliinids of the ' Investi- 

 gator'), and Prof. S. F. Harmer, the species is described 

 here under tlie name of Phormosoma verticillatam, sp. n., the 

 name indicating the most prominent feature of the species, 

 viz. the curious verticillated primary abactinal spines. 



Tlie new species of Arceosoma, which, according to the 

 wish of Professor Bell, I name A. Oicsteni, in lionour of the 

 collector, is especially interesting on account of its primitive 

 " tetradactyle " pedicellnria?. As regards J\Ir. Yoshiwara's 

 two s])ecies, one [Asthenosoma ijimai) proves really to belong 

 to the genus Asi/ienosoma i\s limited by me in the 'Ingolf 

 Echinoidea, the other (A^fhenosoma longispinun{) to the 

 genus Calverio, and it can even scarcely be doubted that it is 

 identical with Calveria gracilis (Agass.). 



1. Aroiosoma Owsteni, sp. n. 

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



The test is rather flexible, of 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 G5 mm. high.) 



The apical area is lather 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 the numerous small anal plates, are covered with 

 spines. The inner anal plates not distinctly elongate. 



