228 



zotrciiiin of a hizoa'cial segment, hut is not iiifretjuently i'oiind on a single zore- 

 cium. The aperture has a small iiidenlation in the middle ol' its proximal margin, 

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

 that of the zou'cia. Each of the lateral surfaces of the gonozod-cium communi- 

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

 numerous rosette-plates, and this chamber, I believe, c()iresj)onds lo the long pedal 

 chamber in the zoa-cium. The covering kenozoa'cium a little dislally lo the aper- 

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

 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-zoo'cial inter- 

 nodes is often interruj)led so that we may (ind several bizocrcial 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-Jl), I>1. XI, ligs. 7a-7c). 



The zooecia large, broad, angularly o\al with a triangularly rounded aper- 

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

 similar to that in C. ucnlricosa, but it is provided with a broailer and more 

 rounded cryptocyst lamina, and immediately on the |)roximal side of the aper- 

 ture we find a transversely j)laced, 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 zoa'cia, and the snjjra-scapular 

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

 the ])osition of the infra-scapular and the pedal chambers are similar lo those in 

 (J. I'ciitricosd, but the two chambers are sci)araled by an obli([ue or nearly verti- 

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

 and the daughler-zocrcium. 



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

 may be contained about 2^/^ limes in the entire length of Ihe covering kenozooe- 

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

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

 molher-zoacium. The aperture has a small sinus in Ihe middle of its proximal 



