164 ECHINODERMS OF THE BRITISH ISLES 



3. Gorgonocephaivs Lamarcki (Miill. and Troschel). (Fig. 93, 1.) 



Disk closely set with small, fine spinelets giving it a smooth, 

 almost velvet3% appearance ; these spinelets continue some dis- 

 tance out on the arms. Underside of arms more or less granu- 

 lated, the ventral plates not showing through the skin in dried 

 specimens. Five arm spines, which are rather coarsely dentate 

 (Fig. 93, 1). Colour in life yellowish- brown. Reaches about the 

 same size as G. caput-medusce. 



In British seas this species has been found in the warm area 

 of the Faroe Channel (60° 11' N., 8° 15' W., 780 m., " Triton " ; 

 recorded under the erroneous name G. eucnemis) ; also the 

 " Michael Sars " has found it here in several places. Probably 

 the G. eucnemis from the Lousy Bank also is G. Lamarcki. It is 

 otherwise known from Finmark to Bergen, Iceland, Greenland, 

 and N. America down to Nova Scotia. Bathymetrical distribu- 

 tion ca. 75-780 m. 



II. Order. Ophiur^ Miiller and Troschel. 



(Syn. Streptophiurce and Zygophiurce Bell.) 



Disk and arms with distinct scales, which may, however, be 

 concealed by grains or spines or by a naked skin. Side arm 

 plates large, not confined to lower edge of arms, often joining in 

 the dorsal and ventral mid-line. Spines not directed downwards, 

 more rarely partly transformed into hooks. The arms, which are 

 always simple, unbranched, are moved mainly in the horizontal 

 direction, the articulation of the vertebrae by means of various 

 pits and processes (" zygospondylous " articulation), mainly 

 alloAving a horizontal movement. Genital shts never vertical, as 

 a rule long and narrow, extending from mouth shield to edge of 

 disk ; rarely each genital slit is divided into an inner and outer 

 part, being coalesced in the middle. Only one madreporite 

 present. 



This order contains the great bulk of the Ophiurans. The very 

 numerous forms are divided into a number of families, of which 

 nine are known to be represented in British seas. Besides these, 

 two more may be expected likewise to be represented there, viz. 

 the Ophioleucidce and the Ophiodermatidce, which would mean that 

 practically all the known families of the order Ophiurae, excepting 

 only the HemieuryaUdae, would be represented in the British 

 seas. The family Ophioleucidae, which is represented in European 

 seas by two genera, is specially mentioned on p. 227 ; the family 



