42 THE VOYAGE OF H.M.S. CHALLENGER. 



a sagittal tentacle is at first very narrow, and the lumen continues slit-like until the 

 insertion of the tentacle is reached. Fig. 7 shows on the right side the slit-like lumen, 

 together with a section of the tentacle, into the base of which it ultimately opens. On 

 the left side, which represents the appearance below the insertion of the sagittal tentacle, 

 the mesenteries are seen to be more important, and the lumen is very large. The 

 reproductive organs are connected with the transverse mesenteries, but the sexual 

 elements are chiefly included in a specialised band of cells, situated obliquely and united 

 to the stomodaeum and body- wall by strands of fibrous tissue. 



Paran tipathes. 



This genus appears to form a connecting link between the Antipathinae and the 

 Schizopathinae, and indicates a mode by which the dimorphic genera may have been 

 derived from such forms as Antipathella, &c. The zooid is enormously elongated 

 in the transverse axis, so that the members of each lateral pair of tentacles are widely 

 separated, and the two near each extremity of a zooid appear to form a pair. The length 

 in the transverse direction is usually four times as great as that in the sagittal. The 

 peristome is somewhat depressed on each side of the oral prominence, so that the zooid is 

 imperfectly divided into three lobes. The whole arrangement is such as might be produced 

 by a great elongation along the sclerobasic axis of such bilateral zooids as frequently occur 

 in the genus Antipathella. Parantipathes larix is evidently allied to Antipathella, and 

 I was at first inclined to regard it as an extreme type of that genus. Besides the most 

 marked elongation of the zooid, in which truly it differs only in degree, there are several 

 other important points in which the species differs from Antipathella, so that I have been 

 induced to institute a new genus for its reception. The elongation of the mouth in the 

 sagittal axis is not well marked, and in its lower section the greatest diameter of the 

 stomodaeum often corresponds with the transverse axis. This, it will be remembered, is 

 the case in Amphianthidae amongst the Actiniaria. 



Horizontal sections through the middle of the oral cone pass also through the upward 

 dilation of the ccelenteron at each extremity of the zooid, the centre of which is occupied 

 by the distal portion of a transverse mesentery. Around the stoniodasum the mesenteries; 

 form an oval figure, the longer axis of which is situated transversely. There are here 

 ten mesenteries of varying breadth. The broadest occupy the transverse axis, the others 

 gradually decreasing in size towards the sagittal axis ; there is a corresponding diminution 

 in the interseptal lumen. This arrangement is shown in fig. 8. A little lower down, just 

 about the point corresponding with the lowest depression of the peristome, the secondary 

 mesenteries extend as for as the body-wall, but soon lose their connection with it. Fig. 

 9 represents a subhorizontal section, in which three of the secondary mesenteries have 

 lost their connection with the body-wall, whilst the fourth still adheres to it. The lower 



