346 R. M. Brydone — Neiu Chalk Polyzoa. 



similar shape but tending towards pointed, ends and spanned by 

 a crossbar dividing it into two nearly equal compartments, the upper 

 being slightly the larger : this seems to separate the species from the 

 M. GriffithilineimdiSiWjitto M. Triminghamensis. (2) Large vicarious 

 inflated, forms of the hourglass type with the external front wall 

 much exaggerated and a very delicate areal rim, sometimes initiating 

 new rows of zooecia, but sometimes occurring in an established, row : 

 these are rare and. delicate and occur very capriciously. 



I have only found this species in the cor-anguinum zone of Kent 

 and Hants, in which it occurs sparingly but well distributed, and 

 once in the TJintacrinus band of Hants. 



Membkanipoea suffkagista, sp. nov. (PI. XXVI, Figs. 3, 4.) 



Zoarium unilaminate, always adherent. 



Zooecia rather small, distinctly subpyriform, with oval areas of 

 average length "38 mm. and breadth '2 to •25 mm. ; side walls wide, 

 bearing a number of stout spine bases with depressions in their upper 

 surfaces but not apparently perforated, and tending to overlap slightly 

 the outer edge of the side wall ; these spine bases are most prominent 

 in the upper part of the zooecia, but appear to occur all round the 

 area, and the spines must have presented, a very militant aspect. 



Ocecia small, very globular, slightly bottle-necked, very regularly 

 present after the earliest stages, but delicate and not often preserved, 

 the specimen shown by Fig. 4 being exceptional. 



Avicularia accessory, strongly triangular and mandibular, with the 

 beak often produced, to a great length in the later stages; a transverse 

 bar divides the triangular aperture into very unequal compartments ; 

 no vicarious avicularia. 



This species might by its spines be ancestral to M. Trimiiighamensis, 

 but by its avicularia it is probably ancestral to J/. GriffitJii. It occurs 

 not infrequently in the cor-angui7ium zone of Kent and Hants and 

 rarely in the Uintacrimis band and Marsupites zone of Hants. 



Membeanipora boletifoemis, sp. nov. (PL XXVL Figs. 5, 6.) 



Zoarium unilaminate, always adherent. 



Zooecia small, slightly subpyriform ; areas strongly oval and usually 

 with a flattened and straight upper end, average length "28 to "33 mm. 

 and breadth '18 to "2 mm. ; side walls typically thin, especially at the 

 upper end. ; in those zooecia, almost exclusively the very early ones, 

 which have no ocecium there may be observed under high magnification 

 a pair of projecting tubules on the side wall at the extreme upper 

 end, and in most zocecia traces of one or even two pairs of pores can 

 be seen in the side walls a little lower down, but these features 

 require a much higher magnification than twelve diameters for making 

 them apparent, and I think they are only relics of discarded 

 appendages. 



Ocecia almost invariably present after the earliest stages, relatively 

 rather large, globular, and slightly bottle-necked, rarely preserved, 

 the specimen shown by Fig. 6 being most exceptional. 



Avicularia of two kinds: (1) The characteristic accessory type, 

 always present, bluntly triangular, with a slightly rounded lower end. 



