BY JAS. P. HILL. 
19 
appear to correspond to the fibres Spengel has observed in 
Balanoq lossus canadensis and B. kupjferi, and which he regards 
as having been carried in, by the infolding of the splanchnic 
epithelium. 
Collar : The epidermis of the collar can, like that of the other 
species of Ptychodera, be divided into five zones (fig. 15 [1-5]). 
Of these the first formed by the anterior free rim of the collar is 
the largest; the second occupies the region of the circular groove; 
the third, that of the circular projecting cushion; the fourth, the 
bottom of the typical ring furrow; while the fifth is formed by 
the narrow projecting rim forming the posterior boundary of the 
collar. The second and fourth zones are similarly constituted; 
they stain darkly with hematoxylin, and as in Ft. minuta they 
contain in their whole depth numerous gland cells; the remaining 
zones contain gland cells only in their outer regions, and stain of 
a lighter colour. 
Collar musculature : It is in this species in its general relations 
essentially similar to that of Ft, minuta. 
In the outer wall of the anterior part of the collar there is the 
usual external layer of longitudinal muscle fibres (figs. 14, 16, l/w.) 
which spring in the posterior part of the collar between the 
longitudinal muscle bundles of the inner wall. Internal to these 
there is the layer of circular fibres which terminate at the 
beginning of the second epidermal zone (figs. 14, 16, cfw.). The 
longitudinal muscles of the inner wall of the collar springing from 
the region of the collar trunk-septum are, as in Ft. minuta, 
separated in the posterior part of the collar into distinct bundles 
by radial fibres passing between the outer and inner walls of the 
collar. The ventro-lateral bundles terminate behind the circular 
vessel fold of the collar, while those more dorsally situated pass 
towards the neck of the proboscis, and are inserted, as in Ft. 
minuta, mainly into the boundaiy membrane of the notochord 
(fig. 16, Urn 1 .; fig. 11, ccp.). The dorsal portion of the longitudinal 
musculature extends, in the posterior region of the collar, round the 
lateral surfaces of the perihpemal spaces, and partly on to the dorsal 
