1915.] NATURAL SCIENCES OF PHILADELPHIA. 61 



arm spines and in the presence of a series of large plates on either 

 side of each arm. 



Astrotoma Lyman (non Koehler). 



As I have referred Koehler's three species, which he placed in 

 Astrotoma, to Astrothamnus, Astrotoma, restr., now includes A. 

 agassizi Lyman, A. murrayi Lyman, A. sobrina Matsumoto, and 

 A. waitei Benham, the first being the genotype. 



Astrotoma sobrina Matsumoto. 



1912, Dobuts. Z. Tokyo, 24, p. 199 (in Japanese). 



Astrotoma murrayi Doderlein (non layman, 1879), Abh. Math.-Phys. Kl. K. 



Bayer. Akad. Wiss., Suppl.-Bd. I, 1911, p. 23, fig. 1, PI. VI, figs. 1 and la, 



PI. VII, figs. 14-146. 



Though the present Japanese form was identified as A. murrayi 

 by Doderlein, I have failed to find any specimen from Japan that 

 strictly corresponds to Lyman's description and figures of the Moluc- 

 can species, so that I am ol^liged to look upon the Japanese form as 

 distinct from A. murrayi. It differs from that species in the much 

 shorter arms, in the narrower brachial lobes of the disk (narrower 

 outwards than inwards), in the longer genital slits, in the fewer and 

 larger stumpy tubercles in the spaces just proximal to the ventral 

 interbrachial areas, and in the comparatively fewer arm spines. 

 The type specimen measures 34 mm. across disk and 200 mm. in arm 

 length, while A. murrayi is described as 29 mm. across the disk and 

 280 mm. in arm leng-th. The brachial lobes of the disk are not so 

 wide as in A. murrayi, and are narrower outwards than inwards, 

 instead of the reverse. The genital slits extend from the inner 

 corners of the ventral interbrachial areas nearly to the disk margin. 

 The spaces just proximal to the ventral interbrachial areas are beset 

 with a few large stumpy tubercles, instead of numerous small ones. 

 First tentacle pore free of arm spines; second with one or two; 

 third, two or three; fourth, three or four; and succeeding, four, or 

 sometimes three. In A. murrayi, four or sometimes five arm spines 

 are present at each tentacle pore, even on the very basal arm joints. 

 However, A. sobrina is very close to A. murrayi, the covering of the 

 disk and arms being quite similar in the two species. But I consider 

 that this similarity is generic rather than specific, as I have observed 

 that the arm covering of the genotype, A. agassizi, is also precisely 

 similar to that of the present species. 



Five specimens; Sagami Sea. 



Order ii. L^EMOPHIURIDA nov. 

 Radial shield and genital plate articulate with each other by 

 means of a transverse ridge or a simple facet on either plate, without 



