470 REVISION OF THE AXIXELLID^, i., 



barely discernible unless stained. The main fibres of the axial 

 skeleton are mostly coarser — up to 90 or 100//, in stoutness — 

 and much more sponginous, and the spicules composing them are 

 less compactly arranged; they form by interunion among them- 

 seh es, and with the aid of lunnerous short connecting fibres, a 

 dense, lattice-like meslnvork, in which the course of the indi- 

 vidual fibies is rather difficult to trace. The extra-axial con- 

 necting fibies occur at irregular intervals, and are either single 

 (spongin-ensheathed) spicules or, more usually, are composed of 

 several (seldom more than five or six) disorderly-arranged spicules 

 interunited by spongin. 



Meyasclere)<. — The megascleres are oxea and relatively few 

 styli, the number of the latter being approximately somewhere 

 between one-fifteenth and one-thirtieth that of the formei' ; 

 among them, an occasional strongyle is also to be met with. 

 They are almost invariably curved, — as a rule a little angulately; 

 are (with the exception of the very stoutest) of uniform, or 

 nearly unif<jrm diameter throughout their length to within 25 /x 

 or less of their extremities; and usually taper thence, either 

 regularly or witli the intermediacy of one or two more or less 

 abruj)t contractions, to a sharp or only slightly njunded-off point. 

 Spicules with much blunted extremities, however, are, in some 

 specimens, Ijy no means uncommon. A certain proportion of 

 the irregularly-ended spicules terminate nuicronately. Among 

 the megascleres of the stalk — rarely, if ever, in other parts of 

 the sponge — occasional (yet constantly occurring) ones are met 

 with which taper almost (or, if stylote, quite) from end to end 

 in one direction, I.e., are markedly anisoactinal. In the stalk, 

 also, the n)egascleres attain to a much greater maxinunn size 

 than elsewhere, and are often slightly more fusiform in shape. 

 In three of the examined specimens (including among them the 

 one with raie microstrongyla) the megascleres are of appioxi- 

 mately the same dimensions — ranging from about 160 (l)ut 

 rarely below 200) to 300 /a in length, and up to 9/x in stoutness, 

 in the branches, and attaining a maximum size of 440 x 15/i. in 

 the stalk: in the fourth specimen — in which, also, the megascleres 



