235 



bers have a rather large, oblong, frontal opening. On the adzooecial side of the 

 daughter-zocecium the three distal chambers have coalesced into a single cavity, 

 and an avicularium is accordingly wanting. The mother-zooecium has a very 

 small, slit-like, infra-scapular adzooecial chamber. 



The ocecium (PI. XII, fig. 1 k). The gonozooecium, which sometimes springs 

 from a mother-zooecium, sometimes from an inserted single zooecium, is approxi- 

 mately of the same size as the covering kenozooecium, and together they are of a 

 broad, hexagonally rounded form with two parallel lateral margins curving in- 

 wards a little. The sternal area has 3 small fenestrse and 3 — 5 spines separated 

 by short fissures. The two distal spines, which meet in the oral suture, have a 

 large inner cavity connected with a large oval pore in the oral margin. The 

 others are very short and generally have no inner cavity. Within the very broad 

 fenestrse of the kenozooecium pores as w^ell as numerous spinous processes are 

 seen, while the supporting processes, which reach the calcareous roof of the keno- 

 zooecium, are most numerous in the portion between the two fenestrse. On the 

 side of these fenestrae we find a continuation of this median portion, which goes 

 as far as the aperture and is bounded by two lateral margins converging towards 

 the latter. A small median chamber may appear on the top of the kenozooecium. 

 It is always found in specimens from the Bass' Strait, in which it is very oblong 

 and provided with one or several slit-like openings in the roof. On the other 

 hand its appearance is very inconstant in colonies from Port Phillip, in which 

 it is very small, oval and only calcified at its base. 



Form of colony. In all the principal branches and sometimes also in some 

 of the secondary branches two bizooecial internodes succeed each other (2, 2, 1, 

 2, 2, 1 . . . .). 



Of this species I have examined colonies from Port Phillip and the Bass' 

 Strait. 



Costicella cuspidata n. sp. 



(PL XX, figs. 6 a-6 c). 

 The Sternal area, which may be longer than the aperture by a half, is provided 

 yyith 7_io small fenestrae disposed in a broad curve, and within these there are 

 6—8 smaller ones, of which one is generally situated in the central line far back. 

 In the central portion of the area we see three, more seldom four spines, of 

 which the two large, plate-shaped distal ones have an inner, most frequently 

 three- or four-branched cavity connected with as many pores, of which we usu- 

 ally find one on each side of the proximal margin of the aperture. Very often, 

 perhaps in most cases, the cavities of the two large spines communicate through 



