236 



a broader or narrower transverse branch. In a small, most often triangular open- 

 ing, situated proximally to the two large spines, we find generally but a single, 

 very short, rudimentary, solid spine, more rarely two. 



The lateral chambers. The supra-scapular chamber has a number of scat- 

 tered pores, and in the proximal part of the basal surface a rounded excision, 

 which is somewhat larger than these. The infra^capular chamber has a small, 

 round or oval opening proximally, and the small pedal chamber an oval or long 

 frontal opening, which is much larger. The mother-zooecium has no adzooecial, 

 infra-scapular chamber. It is characteristic of this species that the last of the 

 zooecia completing a row springing from a daughter-zocecium has a terminal, 

 compressed, narrow, rhombically rounded chamber (PI. XX, fig. 6 b). 



The ooecium. The gonozocecium, which is but half as high as the covering 

 kenozocecium, is sometimes borne by a mother-zooecium, sometimes by an in- 

 serted single zooecium. It is provided with a rather broad but low frontal sinus, 

 which is bounded on either side by a very short somewhat bent spine, and thus 

 the single pair of spines do not meet as in the other species. The sternal area 

 is much reduced and has 5 A'ei-y small fenestrse, situated immediately on the 

 proximal side of the aperture. Along its frontal, central line the covering keno- 

 zocecium is provided with two rather large pores, which may be sometimes single, 

 sometimes more or less deeply divided by a tongue springing from their distal 

 margin. The two groups of pores and spinous processes within the long, lateral 

 fenestrEe meet in a median, generally angularly bent portion, which reaches the 

 proximal of the two median pores. The small, terminal kenozocecium is some- 

 times developed as an avicularium and then communicates with two small 

 cavities. 



Form of colony. In the principal branthes two bizooecial internodes succeed 

 each other (2, 2, 1, 2, 2, 1 . . . .). 



Of this species I have examined colonies from Port Phillip. 



Costicella hastata Busk. 



Catenicella hastata Busk, Voyage of Rattlesnake, I, pag. 355, Catalogue of Marine 



Polyzoa, Part I, p. 7, PI. II, figs. 3, 4. 



(Pi. XII, figs. 1 c, 1 d, 1 f, 1 g, 1 j, PI. XX, figs. 8 a, 8 b). 



The sternal area, which may be about twice the length of the aperture, has 



7 — 9 fenestrse, disposed in a long curve, and as many hollow spines, of which 



each is provided with a pore in or towards the end. Each of the spines in the 



first pair has however often two, which then correspond with a bifui-cate cavity. 



The lateral chambers. The supra-scapular chamber, which may sometimes 



