EXPLANATION OF PLATE 2. 



Fig. 1. Adult worm {Polydora) enlarged under a lens. 



„ 2. Great hooks of the fifth segment of the body ; a, as usually seen in the separated 

 and perfect organ under pressure ; b, more complete as obtained in the living 

 animal or in a favourable spirit preparation x 700 diameters. 



„ 3. Spear-tipped bristles accompanying the former x 700 diameters. 



„ 4. Hooks of the posterior region of the body ; o, pressed between two glasses ; b, seen 

 in front, so as to exhibit both wings, x 700 diameters. 



„ 5. Front and side view of two of the bristles of the same species, x 700 diameters. 



„ 6. Caudal segment and its cup, x 210 diameters. The whole of the figures and 

 explanations after Prof. W. C. Mcintosh. 



