BRYOZOA FROM S.W. VICTORIA, AUSTRALIA. 



327 



for the zooecia originating at the side is an important characteristic. 

 The form of the cell, however, very closely resembles that of Cri- 

 brillina terminata (fig. 68) ; and by the present designation we, at 

 any rate provisionally, show the zocecial relationship and the mode 

 of the zoarial growth. After finding that Schizoporella pliymatopora 

 (fig. 32) showed, when broken, a structure like Bactridium, I re- 

 examined the present fragments, which, however, seem to belong to 

 a form with cells on one side only, growing erect with only one 

 series of cells. The British-Museum specimen of Lepralia monoceros? 

 Busk, shows that the pores in that species also are provided with a 

 denticle ; but in that case the denticles are irregular. 



27. Cribrillina suggkerens, sp. nov. Plate XVII. fig. 75. 



Zoarium in Eschar a-ioim, consisting of two layers of cells grow- 

 ing back to back. Zooecia oval, distinct, quincuncially arranged, with 

 a double row of from twelve to fourteen erect tubular projections 

 on the front, and a smaller row on the side, and some smaller ones 

 in the central area ; large pores between the tubes. Oral aperture 

 small, semicircular, with straight proximal edge ; in one case two 

 curved irregular spines form a sort of arch over the aperture. A 

 short triangular avicularium above the aperture on one side. Two 

 oblong lateral rosette plates, one oblong distal plate. 



Proximal edge of aperture 0*06 millim. wide. 



This is a most curious and instructive form, in which we are at 

 the outset met by a difficulty as to its generic position ; for, looking 

 at the aperture, we find it might belong to Cribrillina or Mucronella. 

 With the latter, however, in other respects there is little in common ; 

 but with Cribrillina we find the radiating character of the pores, 

 and, although no known species has such a bristling surface, yet in 

 C. Gattyce, C. cribrosa, Hell. *, C. figularis, &c. there is a row of 

 slightly raised pores round the edge of the cribriform area. 



These very curious prominent tubes (about 0*07 millim. high) 

 naturally lead to the consideration of the signification of the pores 

 and of avicularia ; for may not avicularia have originated in such 

 tubes having covers? and we may again ask, is the function of 

 these tubes different from that of the pores which we almost univer- 

 sally find on the surface of the Bryozoa ? The physiological signi- 

 fication of these pores is, perhaps, not sufficiently appreciated ; and 

 therefore a moment's digression is necessary, as we may thus have 

 the record even in fossils of physiological structure. When a recent 

 cell is decalcified, the membrane remaining shows small disks where 

 the calcareous pore has been, and a spot in the centre of this disk 

 further shows that to each one a thread of the endosarc has extended ; 

 so now we see that oxygenation, or a similar vitalizing change, takes 

 place by means of the communication with the exterior through these 

 pores. The front of a cell, however, frequently becomes covered 

 with mud or organic growth ; and in such cases raised tubes might 

 be of great advantage in the economy of the colony : and if these 



* See ray fig. 4. pi. ix. in Bry. of Naples (Ann. & Mag. Nat. Hist. ser. 5, 

 vol. iii. 1879), to which I have now to make addition. 



z2 



