256 



axis of the zooecium. The supra-scapular chamber is a very small, low cavity 

 with a triangularly rounded opening situated distally to the inner part of the 

 avicularium. The infra-scapular chamber has an oval opening and is situated 

 proximallj' to the frontal wall of the avicularium. It is principally in communi- 

 cation with the zooecium, from which it is only separated by the small proximal 

 wall of the avicularium. The narrow, likewise frontal, pedal chamber, which in 

 the single zooecia may attain half the length of the latter, is situated proximally 

 and a little frontally to the infra-scapular chamber. There is a small, oval bound- 

 ary chamber (m. Ill) on the bi-zooecial internode, and the pedal chamber on the 

 adzooecial side of the daughter-zooecium is very short, sometimes merely oval. 



The ocecium. The gonozooecium is as in the preceding species a single zooe- 

 cium. The proximal part of its operculum is covered by a thin, labiate process 

 with a straight margin, and its avicularia differ from the ordinary zooecia in 

 having the mandible situated in their roof, so that it forms a right angle with 

 the longitudinal axis of the gonozooecium, while in the ordinary zooecia it is 

 parallel with this axis. The covering zooecium has distally to the aperture of 

 the gonozooecium a rather large, irregularly rounded fenestra, on either side of 

 which we find a long curve of up to 20 small, round spots, which correspond 

 to the continuous belt in the preceding species. 



Form of colony. Uni- and bi-zooecial internodes alternate in such a way, 

 that two bi-zooecial internodes are often separated by two or several single 

 zooecia. 



Colonies from Twofold Bay, St. 163 A, ChaiUenger. The form described essen- 

 tially corresponds with Busk's typical specimen from Bass Straits, which how- 

 ever differs in having larger, somewhat ascending and somewhat frontally turned 

 avicularia. • 



Catenaria cornuta (Busk). 



Catenicella cornuta Busk, Voyage of Rattlesnake, I, pag. 361, Catalogue of 



Marine Polyzoa, Cheilostomata, pag. 11, PI. X, figs. 1, 2. 3. 



(PI. XIII, figs. 5 a, 5 b, PI. XXI, fig. 1 a). 



The zooecia, the breadth of which may be contained about twice in the 

 length, have a frontal surface almost as strongly arched as the basal surface and. 

 on either side a narrow marginal ridge, which bounds the pedal chamber basally. 



The lateral chambers. In the examined colonies it is only in a smaller 

 number of zooecia that the scapular chamber is on one side developed as an 

 avicularium, directed outwards and somewhat basally. Such a chamber may be. 

 found not infrequently on a daughter-zooecium, the corresponding mother-zooecium 



