R. M. Brydone — New Cretaceous Polyzoa. 493 



Cribrillna T-forhis, sp. nov. (PL XXXII, Figs. 2, 3.) 



Zoarium unilaminate, adherent. 



Zocecia rather small, average length - 55 mm. ; primarily they are 

 of the usual type with very low side walls and rather strongly arched 

 front walls traversed by radiating wholly imperforate furrows and 

 a distinctly concave posterior lip to the aperture which is widely 

 lenticular with a broad flat anterior lip ; the farrows are very 

 shallow and sometimes cannot be detected over a whole zocecium ; 

 eight pairs seem to be the standard ; in the secondary stage the side 

 walls rise to a level slightly above the edges of the front walls and 

 coalesce partly, but not wholly ; a denticle forms on the posterior lip 

 of the aperture and develops into a short rather narrow process 

 stretching upwards at a low angle over the aperture and then giving 

 off two branches, one on either side, at right angles to it, which 

 curve downwards and form the posterior lip of the secondary 

 aperture, whereby hiding the primary aperture ; finally, the outer 

 edge of the anterior lip of the primary aperture is produced forwards 

 and raised slightly to form the thin anterior lip of the secondary 

 aperture, which is in a highly inclined plane. "When the light is 

 from the foot of the zocecium the anterior secondary lip, if formed, 

 may be, and the primary anterior lip, if the secondary one has not 

 been formed, is almost sure to be, invisible in shadow, and the 

 zocscium appears to end abruptly in a suspended T, which is very 

 distinctive. 



Ocecia scarce, rather flatly globose, rather large in proportion, 

 with a wide aperture cut back rather sharply and squarely ; some- 

 times the anterior lip of the secondary aperture rises and embraces 

 the greater part of them. 



Avicularia small, beak-shaped, with spatulate anterior ends when 

 well developed, but accessory beak-shaped avicularia vary so much 

 in a single zocecium, according to their opportunities for development 

 and their state of preservation, that no importance can be attached to 

 variations in their appearance ; they are scattered irregularly along 

 the side walls, but tend to occur in pairs pointing towards the 

 aperture from below and just touching the anterior lip. 



This species occurs in the zone of Offaster pilula in Hants and 

 Sussex and does not appear to survive that zone, nor in those counties 

 to have any successor in the (restricted) zone of A. qtiadratus, but in 

 the top beds of that zone in Suffolk it is succeeded by 



Cribrilina Bramfordestsis, sp. nov. (PL XXXII, Figs. 4, 5.) 



This species is so closely allied to the preceding one that it is most 

 easily described by enumerating the differences between them. 

 C. Bramfordensis differs from C. T-formis in its greater size (average 

 length - 8 mm.), its furrows deeply and squarely cut at the outer ends 

 and more numerous (nine or ten pairs being a minimum, while the 

 numerous small ones which can sometimes be detected round the 

 anterior end, coupled with the increase in numbers which automati- 

 cally accompanies any accidental increase in length, make it 

 difficult to put any limit to the number that might be met with), the 

 abundance of ocecia which are regularly overridden by the wide 



