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'ENDEAVOUR' SCIENTIFIC RESULTS. 



are scattered between them. The spicules of the main fibres,, 

 which are seldom more, and usually much less than ten in 

 number in a cross section of the fibre, are sometimes collected 

 into a slender compact axial strand, and sometimes spread 

 dispersedlv ; in the connecting fibres they 

 are arranged uniserially or, less fre- 

 quently, pauciserially. Acanthostyles are 

 of rather rare occurrence ; mostly they 

 echinate the fibres, but a small proportion 

 occur within the fibres and an occasional 

 one is met with interstitially. The meshes 

 of the reticulation are very variable in size 

 and shape ; their angles are usually well 

 rounded off, and the apertures of the 

 smallest meshes are consequently oval in 

 outline. The pattern of the skeleton, as 

 seen in section, differs to a great extent 

 according to the direction in which the 

 section has been cut. The minimum de- 

 gree of irregularitv is shown in sections 

 cut perpendicularly to the plane of a 

 lamina and in the direction of growth ; in 

 such sections the repeatedly branching 

 main fibres run longitudinally in a very 

 irregular manner and are joined by single 

 transverse fibres or by interreticulations 

 (of lesser or greater extent) of connecting 

 fibres, according as they lie close together 

 or farther apart. The meshes of the reti- 

 culation are tympanised by filmy mem- 

 branes to which the interstitial spicules 

 appear to be entirely confined. Possibly 

 these membranes are capable of being per- 

 ceived only in sections prepared from dry 

 specimens, such as the present are. 



Fig. 50— JV. conec- 

 tens a, b Styli, show- 

 ing the extremes of 

 form exhibited by 

 these spicules. c 



Megascleres. — 



(i.) Smooth, normally straight, cylin- 



Chela. 

 figured.) 



drical styli or less frequently sub- 

 tylostyli, varying in length from 

 (Toxa not about 130 to 250 }i, and in dia- 



meter up to 4 |<. They show a 

 barely appreciable degree of differentiation into two- 

 orders : those which exceed 200 ji in length are 

 seldom more than 3 and never more than 3.5 }i in- 

 diameter, and are usually tornotely pointed ; whilst a 

 considerable proportion of those below 180 ji in length 

 may attain a diameter of 4 n, and commence to- 



