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



are a glossy black, but in all other parts the sclerenchyma.has a uniform reddish brown 

 colour. The spines are moderately long, round, and taper slowly to a sharp point. Each 

 spine is covered with numerous small sharp-pointed processes to near its base. The 

 spines are rather crowded and extend subhorizontally, or some may be tilted up at an 

 acute angle with the axis. No well-marked spiral arrangement is observable, but six 

 longitudinal rows may be counted from one aspect of a pinnule (PL III. figs. 8 and 8a). 

 The members of a row are a little over one length apart. 



The polyps (PL III. fig. 9) vary considerably in size, those on the branchlets being 

 usually larger and more distant than those on the pinnules. The whole of the peristome 

 within the tentacles forms a large mammiform process, on the centre of which the mouth 

 opens. The mouth is usually, but not invariably, elongated in the sagittal axis ; some- 

 times the aperture is dumb-bell shaped. The tentacles form six small tubercles arranged 

 radiately around the mouth, or in elongate polyps they form three pairs, viz., two lateral 

 pairs, which are close together, and a sagittal pair ; the two members of a pair are 

 separated in each case by the diameter of the peristome. In spirit preparations the 

 spines project freely through the ccenenchyma, and in many cases also through the zooidal 

 tissues. A comparison of the shape of the polyps situated on the pinnules with those 

 on the branchlets would lead one to suppose that during the growth of the colony the 

 polyps when at first formed have an elongate outline, but that afterwards, with an 

 increase in the thickness of the axis, a more radiate outline is assumed. Apparently the 

 polyps, which are about twice as broad as long on the pinnules, attain their full diameter 

 in the transverse axis in such situations. Later, with an increase in the thickness of the 

 sclerenchyma, the diameter in the sagittal axis gradually increases until the outline is 

 practically round. The polyps on a pinnule may be crowded or relatively far apart ; 

 those on the branchlets are usually about one diameter apart. 



Habitat.— Station 192 ; September 26, 1874 ; lat. 5° 49' 15" S., long. 132° 14' 15" E., 

 off Ki Islands ; depth, 140 fathoms ; bottom, blue mud. Two specimens. 



Genus Tylopathes, n. gen. 



? Antipathes {pars), Pallas, &c. 

 1 Rhipidipathes (pars), M.-Edw. 



Polyps small and isolated, appearing as oval or oblong cushion-like elevations on the 

 ccenenchyma. The mouth is situated on a small median prominence and is usually slit- 

 like. The tentacles are moderately long, or may be reduced to very short knobbed 

 elevations of the margin of the peristome. The polyps are somewhat of the Aphanipathes 

 type, but, though flattened, their contour is never obscured by projecting spines. The 

 reproductive elements are contained in specialised bands of cells attached to the stomo- 

 dseum and body- wall as in the genus Antipathes. 



