228 



zocecium of a bizooecial segment, but is not infrequently found on a single zoce- 

 cium. The aperture has a small indentation in the middle of its proximal margin, 

 while the structure of the sternal area and its cryptocyst lamina is similar to 

 that of the zooecia. Each of the lateral surfaces of the gonozocecium communi- 

 cates in the whole of its length with a large, long, lateral chamber provided with 

 numerous rosette-plates, and this chamber, I believe, corresponds to the long pedal 

 chamber in the zocecium. The covering kenozooecium a little distally to the aper- 

 ture has a transversely oval fenestra on each side through which the real ooecium 

 can be seen, and above each fenestra a small avicularium, which on the inner 

 side is in communication with a supra-scapular and on the outer and basal side 

 with an infra-scapular chamber. 



Form of colony. The regular alternation of the uni- and bi-zooecial inter- 

 nodes is often interrupted so that we may find several bizooecial internodes suc- 

 ceeding each other. 



Of this species I have examined colonies from the Bass' Strait. 



Scuticella maculata Busk. 



Catenicella ventricosa (var. maculata) Busk, Catalogue of Marine Polyzoa, 



Cheilostomata, PI. Ill, fig. 4. 



(PI. XX, figs. 4a-4b, PI. XI, figs. 7a-7c). 



The zooecia large, broad, angularly oval with a triangularly rounded aper- 

 ture, which has an almost straight margin. The sternal area is of a structure 

 similar to that in C. ventricosa, but it is provided with a broader and more 

 rounded cryptocyst lamina, and immediately on the proximal side of the aper- 

 ture we find a transversely placed, inner cavity opening out into the aperture on 

 either side of the short sutural line. • 



The lateral chambers. The scapular chamber is generally developed as an 

 avicularium only on the outer side of the single zooecia, and the supra-scapular 

 chamber has a steeply ascending, pointed, calcified outer wall. The form and 

 the position of the infra-scapular and the pedal chambers are similar to those in 

 C. ventricosa, but the two chambers are separated by an oblique or nearly verti- 

 cal wall. Here too we find a long, narrow boundary chamber between the mother- 

 and the daughter-zooecium. 



The ooecium (PI. XI, figs. 7 a— 7 c). The gonozocecium, the length of which 

 may be contained about 2V2 times in the entire length of the covering kenozooe- 

 cium, is generally situated at the end of a branch formed by 1—4 zooecia spring- 

 ing from a mother-zooecium, and more seldom takes its origin directly from a 

 mother-zooecium. The aperture has a small sinus in ihe middle of its proximal 



