TFIE MORPHOLOGY OF TFIE CHFJLOSTOMATA. -iOo 



since a layer of nuclei can be seen superficial to it. The 

 parietal muscles are very delicate. The occlnsor muscles 

 originate from the distal wall, but I have not certainly seen 

 divaricator muscles. 



Schizoporella s an guinea,, Norman (fig. 46). 



This is the form described by Waters/ in his paper on the 

 Polyzoa of Naples, as Lepralia pertusa, var. sinnata. 



The operculum is rather stronger than in S. linearis, and 

 it has a well-marked marginal sclerite which is distinctly' 

 thickeued at the points where if articulates with the condyles. 

 The compensation-sac (fig. 46, c. s.) is beautifullj^ shown in 

 specimens from which the basal wall has been removed. 

 The parietal mnscles radiate into its lateral walls, and the 

 external parts of its basal wall, from the lateral and proximal 

 walls of the zooecium. The distal parietal muscles {p.m.'), 

 which stretch transversely across the zooecium, probablv act 

 as divaricators. 



Dry specimens show the epitheca, stretched over the tuber- 

 cles of the reticulately thickened frontal shield. 



Schizoporella australis, Haswell.~ 

 This species is characterised by having an elongated avicu- 

 larium on the proximal side of the orifice, with an acute 

 mandible directed obliqnely towards the proximal end of the 

 zooecium when closed. The condyles are strong, and have 

 denticulated edges (fig. 47). The continuity of the fioor 

 of the compensation-sac with the sinus of the operculum is 

 clearly seen in the preparations. The sac resembles that of 

 S. linearis. 



Urceolipora nana,^ MacGilL, 1881. 

 The operculum is Schizoporel la-like. At its proximal 

 border opens a large compensation-sac which extends nearly 



' ' Ami. Ma-. Nat. Ili^t.' (5), iii, 1879, p. 31, pi. viii, fig. 5. 



2 ' Proc. Linn. Soc. N. ?. Wales,' v, ISSl, p. 11. 



3 MacGillivray, • Prodr. Zool. Vict.,' Dec. xi, 1885, p. 19; Busk (I88J.), 

 p. 82 (as Caly nimopliora lucid a). 



