193 



the cryptocyst, and the two belonging to the same zooecium may sometimes 

 nearly reach each other. Contrary to the rule each distal wall is furnished with 

 two multiporous rosette-plates. 



Spicules. Only compasses are found, measuring from 0,053 to 0,265"""- and 

 varying greatly with respect to the angle made by the legs. While the angle in 

 the smaller ones is about 113», it approaches 180" in the longest, which are only 

 found in the zooecial cavity. 



Ooecia are not found. 



The avicularia, occurring less numerously among the zooecia and only about 

 half as large as the latter, are quadrangular or pentagonal, and the triangular 

 mandible has rather curved lateral margins. 



Of this species I have examined two dry colonies from Port Phillip, found 

 in the collections of Algae at the Botanical Museum. The zooecia of the two colo- 

 nies, which form a covering on cylindrical algal stems, are arranged in an- 

 nular belts. 



Thalamoporella Jervoisi Hincks. 

 Steganoporella Jervoisi Hincks, Annals Nat. Hist., ser. 5, Vol. VI, 

 1880, pag. 30, PL X, fig. 9. 

 (PI. Via, figs. 4 a— 4 e). 

 The length of the zooecia varies between 0,532 and 0,798"""- The aperture, the 

 length of which may be contained 3 — 4 times in the whole length of the zooe- 

 cium, is unusually long and has a very slightly developed, sometimes almost 

 imperceptible sinus small both in depth and breadth. The operculum, the chitinous 

 arch of which is strongly developed, has a continuous, distally curved proximal 

 sclerite and a gi-eater or lesser part of the membrane filling the proximal part 

 of the aperture is chitinized together with the operculum (not to be seen in the 

 figure 4 c, which does not show either the thin marginal portion outside the 

 opercular arch), the proximal margin being in this way either straight or a little 

 convex. Each of the lateral margins has a slight incurvation and within this the 

 opercular arch is provided with a small process for muscular attachment. The 

 sharply defined adoral areas are well developed with large, cone-shaped-cylindrical, 

 somewhat compressed acropetal spines. Of the two opesiulse the larger is gener- 

 ally very narrow, almost slit-like and pointing obliquely and inwardly to\^ards 

 the proximal end. The other is very small. The opesiular outgrowths both reach 

 the basal wall, the larger touching it in an open, hook-shaped curved line, while 

 the other meets it in a very short, ascending line. The cryptocyst the central 

 part of which is much depressed lacks a raised marginal portion and is most 



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