54 W. G. RIDEWOOD. 
Buccal Shield. 
The shield of the adult polypide of C. hodgsoni varies in size, but on an average 
of a great many cases measures 1°2 by 1°2 mm. (text-fig. 17, E). The antero-posterior 
diameter, however, may be as much as ‘2 or ‘3 mm. longer or shorter than the 
maximum width, the organ being evidently capable of great contortion in all 
directions. The posterior lobe is equal in width to the front lobe, or is slightly 
less ; the centre of the red line is about four-fifths or five-sixths of the antero-posterior 
diameter from the front edge. The diagram given in text-figure 17, E is a composite 
figure of about twenty specimens. 7 
C. 
Trxt-FicuRE 17.—A = Buccal shield of a bud of C. hodgsoni with two pairs of plume-axes only. B = Shield of a bud 
with the fourth pair of plume-axes making their appearance as hemispherical projections. C = Shield of a bud 
with the fifth pair of plume-axes making their appearance as hemispherical projections. D = Shield of a bud with 
the sixth plume-axes about twice as long as broad, and without pinnules. E = Shield of adult polypide of 
C. hodgsoni. F = Shield of adult polypide of C. dodecalophus. These six figures are drawn to the same 
scale (x 40). 
The red line makes its first appearance in the bud at a time when the fourth 
plume-axes have the form of hemispherical prominences at the base of the third pair. 
It is at this period only a short line extending across not more than one-third or 
one-half of the total width of the shield (text-fig. 17, B), and it is in this stage 
and for some time later relatively more remote from the posterior edge of the shield 
than it is in the adult (cf. text-fig. 17, B, C, D, E); the posterior lobe does not 
enlarge quite so rapidly as the anterior lobe as growth proceeds. Until the stage 
at which the fifth pair of plume-axes normally make their appearance—they are in 
