254 



concave, thickened, protruding, proximal rim, has two well-developed, conspicuous 

 hinge-teeth and is closed finally by three (one distal and two proximal) calcareous 

 processes, springing from its inner margin and meeting in the centre. The pedal 

 chambers, at any rate those of the single zocEcia and the mother-zooecia, are very 

 long, narrow and their frontal wall is quite uncalcified. 



The peculiar occlusion we find in this genus is similar to that in Melicertites 

 Royana pointed out by Waters^- Here also it is brought about by means of 

 3 — 4 calcareous processes, which meet in the centre of the aperture. If there are 

 three, which is usually the case, they are however disposed in a different way 

 from in the species of the genus Catenaria, as in the above species there are two 

 distal and one proximal. The type-species of this genus is Cat. Contei And., of 

 which Mr. Waters^ has recently given a description. 



Catenaria formosa Busk. 



Catenicella formosa Busk, Voyage of Battlesnake, I, pag. 360, Catalogue of Marine 



Polyzoa, Cheilostomata, pag. 9, PI. VII, figs. 1, 2. 



(PI. XXI, fig. 3 a, PI. XIII, fig. 2 a). 



The zooecia, the breadth of which may be contained 1^2 times in the length, 

 are of a robust, angularly oval form, and the boundary between the flat frontal 

 wall and the arched basal wall is formed on either side bj' a distinct marginal 

 ridge. The aperture is provided with a proximal, strongly concave margin. 



The lateral chambers. The scapular chamber, which in most zooecia seems 

 to be developed as an avicularium with a small mandible, is large, compressed, 

 somewhat ascending and protruding almost straight outwards, being only slightly 

 inclined frontally. The supra-scapular chamber is a low, narrow cavity, provided 

 with a membranous roof in the whole of its length. The infra-scapular chamber 

 is a small, wholly frontal cavity with a circular opening, through the centre of 

 which the septum between the zocecium and the avicularium can be seen; and 

 the pedal chamber, which attains an unusually large breadth, though but seldom 

 more than half the length of the zocecium, is likewise fi'ontal and has its start- 

 ing point somewhat proximally to the opening of the infra-scapular chamber. It 

 is considerably smaller on the daughter-zooecium than on the other zooecia and 

 especially very small and oval on its adzooecial side. In the bizocecial joint we 

 find a pear-shaped or oval boundary chamber (m. III). The adzooecial side of 

 the daughter-zooecium is generally provided with an avicularium and the ad- 



' 108 a, p. 52. 2 116 a, p. 130. 



