436 R. M. Br y done — New Chalk Polyzoa. 



III. NOTKS ON NEW OE IMPERFECTLY KNOWN ChALK PoLYZOA. 



By K. M. Brydone, F.G.S. 



[Continued from the June Number, p. 250.) 

 (PLATE XIV.) 



Cribrilina Gregory!, mihi.' (PI. XIV, Figs. 1-3.) 

 TFIHE original figure of this species was rather diagrammatic and 

 I requires supplementing. Figs. 1 and 2 are from the type-specimen, 

 Fig. 2 being given to illustrate the rectangular aperture which the 

 species lias a tendency to develop, though quite irregulaxiy ; this 

 rectangular outline appears to be due to the amalgamation of the two 

 prominent tubercles into a straight-edged cap which liides the arched 

 part of the upper lip and may be ooecial in function. The typical 

 form of the species is definitely established in the Marsupites zone 

 (^ = Marsupites band of many authors), though it only becomes 

 abundant in the succeeding zone. 



Fig. 3 illustrates a form which occurs sparingly in the upper part 

 of the zone of M. cor-anguinum, free-growing specimens of which 

 have the strongly punctate basal lamina of this species, and which. 

 I regard as probably a developmental stage of it; distinct traces are 

 shown of an apertuz-e with six tubercles on the upper lip, four of 

 which fail to persist. 



Cribrilina suefulta, sp. nov. (PI. XIV, Figs. 4, 5.) 



Zoarium unilaminate, adherent. 



Zooecia practically zooecia of a typical pyriform Memhranipora such as 

 31. Triminghamensis, mihi^ with a highly arched Cribrilinid front 

 wall added ; the front wall is in two sections, divided longitudinally 

 by a stout rib ; the outer section rises at a steep angle from the side 

 walls to support this rib, and is pierced by a series of narrow 

 radiating slits ; the inner section is enclosed by a row of pores along 

 the inner side of the rib, corresponding very regularly with the slits 

 outside ; it is markedly depressed and has a few pores scattered 

 irregularly over it; the aperture is roughly semicircular, its lower 

 lip being strongly arched, as it is formed by the thickened edge of 

 the arched front wall, while its upper lip is flat and bears very faint 

 tubercles, apparently five in number normally. 



Ooecia probably represented by wide, shallow, hood-like swellings 

 of the upper lip, having a straight free edge, which make the 

 apparent outline of the aperture quite sharply oblong. 



Avicularia corresponding very closely in shape, size, and disposition 

 with those of C. Gregoryi. 



This species occurs in the cor-anguinum zone and Uintacrinus band 

 sparingly, and I have a specimen from the zone of 0. pilula (sub- 

 zone of abundant 0. pilula). It is obviously intermediate between 

 Crihrilina and Memhraniporella, and, in accordance with my previous 

 practice in such cases, I have attributed it to the former. 



The normal aspect of the species (Fig. 4) presents little obvious 

 relationship to C. Gregoryi, but in Fig. 5 I have illustrated a specimen 

 which I think must be regarded as a coarse form of C.suffulta, and which 

 1 Geol. Mag., 1906, pp. 289-300. 



