Gatly Marine Lahoratory ^ St. Andrews. 151 



make its tunnel in shells. In Nevaya a fully developed foot 

 witli lamellae and bristles occurs in front of that with the 

 four great golden bristles inserted in the massive setigerous 

 region. Moreover, no bifid or fork-like bristles occur in 

 Nevaya so far as the single example shows. Both Sclero- 

 cheilus and Nevaya present a remarkable development of 

 certain anterior ventral bristles which must in some way be 

 connected with their dwellings, whether in tubes or burrows ; 

 yet the divergences in the position and structnre of these 

 organs in each case indicate noteworthy differences in 

 function. In Polydora the great hook-like bristles occur on 

 the fifth segment, whereas homologous forms are on the 

 third foot of Disoma. De St. Joseph after a careful survey 

 of the structure of Sclerocheilus concludes that it belongs to 

 the Scalibrcgmidpe. 



3. On the British Cirratulidre. 



Four species representing the Cirratulidaj are given in 

 Dr. Johnston's ' Catalogue of Worms in the British Museum,' 

 viz. Cirratulus tentaculatus, jNIontagu, Cirratulus cirratus, 

 O. F. Miiller (under the name of C. borealis), Aonis vittata, 

 Grube, and Dodecaceria concharwn, (Ersted. 



By De Quatrefages the Cirratulids were classified chiefly 

 by the arrangement of their bi'anchiae, which either occurred 

 throughout or were confined to the anterior segment ; but 

 subsequent authors took into consideration the structure of 

 the bristles and hooks, as shown, for instance, by Langer- 

 hans, Levinsen, Clapar^de, and others. Thus two great 

 divisions of the Cirratulids are made by De St. Joseph, viz. : 

 (1) those devoid of large prehensile tentacles, and (2) those 

 having such. Further, they may be grouped : (1) into those 

 having capillary bristles in both divisions of the foot 

 throughout, (2) those having only capillary bristles in the 

 dorsal division and crotchets in a certain number of the 

 ventral divisions, and (3) those having capillary bristles and 

 crotchets in a certain number of both dorsal and ventral 

 divisions. The majority of the British forms fall under the 

 third group, such as Cirratulus cirratus, C. tentaculatus, 

 C. bioculatus, Dodecaceria concharum, and Choetozone. 



C. tentaculatus is everywhere distributed round our shores 

 from Shetland to the Channel Islands, and is abundant 

 under stones on muddy and sandy ground between tide- 

 marks. Such muddy sand, indeed, is often furrowed by 

 them and their trailing tentacles, which stretch as orange 

 threads in every direction ; and, besides, they are found in 



