334 AET, 2. — H. MATSUMOTO : 



aa — Very small, secondary dorsal accessory xDlates present besides the 

 two large ones OpMocrasis. 



OpliiodOTis pericalles Clark. 



Opliiodoris pericalles : Clark, Bull. U. S. Nat. Mus., LXXV, 1911, ]). 

 177, fig 80. 



Off Osé Zald, Suruga Gulf; 65 fathoms (Clark). Eastern 

 Sea ; 95-106 fathoms (Clark). 



Key to Japanese species of OpMoneveis.^^ 



A — Genital papillas x^i'esent ; ventral arm plates without median notch 



and eminence. 

 (( — Disk scales coarse ; dorsal arm plates not very wide, slightly wider 



than long ; three arm spines porrecta. 



aa — Disk scales very fine ; dorsal arm plates very wide, twice as wide 



as long or wider ; four arm spines in the basal arm joints 



eurybracJdplax. 



A A — Genital papillae absent ; ventral arm plates with a median notch 

 and eminence sinensis. 



Ojyliioueveis porrecta Lyman. 



OpMonereis porrecta : Lyman, Proc. Boston Soc. Nat. Hist., VII, 1860, 

 p. 260-) ; Lyman, 111. Cat. Mus. Comp. Zool., I, 1865, p. 147, figs. 14 & 15 ; 

 Lyman, Rep. Challenger, V, 1882, p. 161; Brock, Zeitschr. wiss. Zool., 

 XLVIII, 1888, p. 495; Kœhler, Bull. Sei. Fr. Belg., XXXI, 1898, p. 74; 

 KcEHLER, Exp. Siboga, XLV, Pt. 2, 1905, p. 53. 



1) CiiAKK, 1915, lias recorded OpMonereis dubia from •' Japan ; mouth of the Bay of Yeddo " 

 ( = Gulf of Tokyo). If his record is based upon Prof. Morse's specimens, it is probably not 

 0. dubia but Opldocrasis marldanneri. Some specimens of the last mentioned species in the 

 Zoological Institute, Imperial University of Tokyo, were also labelled " OpMonereis dtibia var." 

 by Rrof. Morse. I have yet to find a specimen of 0. dubia from the Aicinity of the mouth of 

 the Gulf of Tokyo, though OpMocrasis marJdanneri is very common there. 



2) This paper was not seen by me. 



