146 R. M. Brijihne—New Chalk Polijzoa. 



development would seem to have proved unprofitable, as it is not 

 repeated, so far as I know, at any later horizon, although the species 

 persisted in Escharine habit to the top of the English Chalk in 

 unabated abundance. But even if this species were grouped on 

 /iccount of its early behaviour with the two following, the group 

 so constituted would be still quite homogeneous, though not so 

 strikingly. 



Had a genus Multeschara been in existence I should have gladly 

 referred my new species to it, for they are so notably smaller than the 

 average run of Escharine forms that such a treatment would have 

 recognized a very large measure of common zooecial as well as zoarial 

 character. As it is they are zooecially Khagasostomata, and I leave 

 them there. 



EuAGASosTOMA Sdssexiense, sp. nov. (PL VII, Figs. 1-6.) 



Zoarium concentrically multilaminate, branching and very massive ; 

 the section figured, which is about 4 cm. in its narrowest dimension, 

 is from a specimen little above the average. 



Zooecia subpyriform, very small, ranging freely in length between 

 •32 mm. and -38 mm. ; aperture semicircular, with a short rectangular 

 tongue about three-fourths of the width of the aperture projecting into 

 it from tlie lower margin, leaving a wide deep sinus at either end. 



Ocecia very doubtfully [)resent ; but a rounded depression occasionally 

 observable at the lower end of a zooecium may be a relic of an ooecium 

 connected with the preceding zooecium. 



Avicidaria shuttle-shaped, with the front wall between the apex 

 and the aperture flush with the side walls ; the aperture is central 

 and shaped like a rounded arrow-head, and the sinus which forms the 

 stem of the arrow-head is very narrow and ends in a tiny circular pore. 



The species is very prone to ectocystal development ; Fig. 4 shows 

 a specimen in which the avicularia dwarf the zooecia. Fig. 5 a specimen 

 ■in which the reverse occurs. 



Abundant at Seaford and Eeachy Head in the upper part of the 

 M. cor-testudinarium zone (= Howe's lower one-fourth of the M. cor- 

 angumum zone), but very difficult to clean perfectly, the chalk being 

 tenacious. I have not yet observed it elsewhere. 



linAGASOSTOMA PALPIGERUM, Sp. nOV. (PI. VII, FigS. 7-10.) 



Zoarium branching, with wide but flattish and rather fragile stem. 



Zooecia small, very variable in dimensions, "4 mm. being a fair 

 average length, but "35 mm. on the one hand or '5 mm. on the other 

 being easily found ; aperture heel-shaped, with a slightly incurved 

 lower margin ; from its corners two long and narrow slits run in 

 a direction at first outwards and downwards, but quickly bending 

 round to straight downwards; the zocEcia remain always distinguishable 

 from one another. 



Ocecia large, rather straight-sided, very high at the apertural end, 

 which is heavily cut back, giving a deeply concave free edge. 



Avicidaria angular, widest round the apertuie, with a long, slender, 

 tapering beak with a median furrow ; the aperture is roughly 



