16 W. G. RIDEWOOD. 
- 
The red line of the shield which is so conspicuous and constant a feature of 
Cephalodiscus does not seem to be present in Rhabdopleura. Schepotieff shows, in 
the exact position occupied by the red line in Cephalodiscus, a “ Pigmentstreif” (1904, 
pl. 2, fig. 9, and 1905, p. 796, fig. 1), but since he says nothing about red colour, one 
is led to conclude that the pigment-stripe is black. The crowd of black pigment spots 
at the anterior point of the shield of Rhabdopleura, assumed to be a rudimentary organ 
of vision, finds no equivalent in Cephalodiscus. The relations of the shield to the 
mouth, however, and the great mobility of the shield, and the glandular nature of 
Trxt-FicurE 8.—Rhabdopleura normani, a polypide greatly enlarged. (Copied from Lankester, 18, plate 38, 
fig. 1.) 
a, mouth; b, anus; c¢, polypide stalk; d, buccal shield; e, plume; f, visceral mass. 
the thick central part of the ventral wall of the shield (Schepotieff, 1905), are the 
same in both Rhabdopleura and Cephalodiscus. 
The coilar region is produced in both into a postoral lamella and plumes. The 
latter are two in number in Rhabdopleura, and although Cephalodiscus has in most 
cases four pairs or more, Harmer’s discovery of male polypides of C. sibogae with one 
pair of plumes only ({0, p. 84) is of interest in this connection, in spite of the fact 
that such plumes do not possess pinnules. 
