166 



Transactions, 



The plane of the hook is not in that of the shaft ; it is " warped,'" as 

 it were. ; the axis of the hook is itself bent, so that the tip lies in a different 

 plane from the rest ; hence when it is mounted and covered some distor- 

 tion is almost sure to occur, if not even a slight rupture at the angle where 

 the hook passes into the shaft. 



The shaft is crossed by transverse lines or grooves at fairly regular and 

 close intervals in the distal region, but lower down they are more widely 

 distant. It is also densely striated in a longitudinal but slightly oblique 



Fig. 5. 



Fig. 6. 



Fig. 



5. — Portions of two hooks which were lying close together 

 in a preparation (very highly magnified). The direction 

 of the striations of the substance of the chaeta is dis- 

 turbed in A, and at the margins the material is slightly 

 ruptured, giving the impression of an articulation when 

 seen under a lower magnification. The delicacy of 

 these lines can scarcely be reproduced, a, shaft ; 6, the 

 claw of the hook. 

 Fig. 6. — One of the ventral hooks from a Kermadec specimen, 

 with the minute capillary bristles at its base. The 

 " sheath " has been omitted. (All the figures of hooks 

 were drawn by aid of the camera lucida.) This hook 

 resembles Elders' fig. 5, pi. vii, of ' L F. lingulata." 



direction ; these striae do not reach the surface of the chaeta. The claw- 

 like end is similarly obliquely striated, and at the angle of bending a 

 disturbance of the direction of these striations occurs (fig. 5). Sometimes 

 there is a small notch on one or on both sides at this point ; in other cases 

 this is absent. 



Each hook is accompanied by 4 very fine short capillaries, usually two 

 above and two below it (as if it were an aciculum in an errant Polychaete). 

 The free ends of these are curved, and lie close to the chaeta, and some- 

 times they may be concealed by the hook if one happens to cut off too much 

 of the body- wall (fig. 6). 



The hook and its satellites are enclosed in a transparent sheath of a 

 cuticle-like structure. This is more readily seen in freshly mounted hooks 

 than in those that have been long in glycerine. The sheath exhibits a 

 corrugation at the surface of the chaeta, but is externally smooth : probably 



