478 



REVISION OF THE AXINELLID.j:^ i., 



The surface is minutely granular. The oscula are scattered 

 irregularly, and \-ary in diameter from ()-8 to 0-75 mm. The 

 colour superficially is pale brownish-grey. The dermal pores (PI. 

 xxvi., figs. 3, 6; PI. xxvii., fig. 4) are for the most part scattered 

 singly and irregularly, as in the variety davatus, but here and 

 there, especially on some parts of the surface, they exhibit also a 

 tendency to become arranged several together in incipiently sie\e- 

 like groups; they range from 40 to 1 10/x in diameter. The dermal 



membrane is rarely, if ever, more than 50 or 

 60/v, in thickness; and the dermal spirula? 

 are confined to a superficial layer which is at 

 most 2f)jh in thickness. 



Examined in its entirety, the prepared 

 skeleton (PL xxiii., fig.4) is of a pale golden- 

 yellow colour, fine-textured, and of soft feel, 

 and of denser appearance extra-axially than 

 that of any other of the varieties or species 

 owing to the greater numbei' and closer 

 arrangement of the radial and coiuiecting 

 fibres, which quite conceal the axial core 

 from view; the core itself is less dense than 

 that of the other varieties. The radial 

 fibi-es, \\hich are of slightly lesser length 

 than the diameter of the core, are mostly 

 between 30 and 50 /x — i-arely as much as 60/x 

 — in stoutness, and are seldom provided with j. 

 spongiu suificient in quantity to form a dis- 

 tinct ensheathing layer. 



The megascleres in the uppermost part of 

 the branches consist almost entirely of 

 strongyla and blunt-pointed oxea (the former 

 somewhat the more numerous), and rarely if ever exceed 300 by 

 7-5/x in size; the length of the shortest spicules is less than 150/x, 

 and individuals below 200 /x in length are common. At the 



Text-fig. 



*]Trachydadus diyitatns var. strongylatuH. ilegascleres. 



