154 E. M. Bri/done— Chalk Polyzoa. 



one can be seen in the upper left-hand part of PI. I!X, Fig. 1, near the 

 margin. 



Vibracularia set very deep between the zocecia, whose bulging sides 

 as a rule overhang them sufficient!} 7 to hide part of the aperture, 

 which is long and narrow, rounded above but tending to be pointed 

 below ; below the aperture the front wall usually rises quickly to 

 a point between converging zocecia ; above the aperture the front 

 wall usually rises very little and abuts at some depth against the 

 succeeding zooecium of one of the adjoining lines. 



In general structure this species is closely related to the form 

 described by Beissel as P. costata, D'Orb., but is easily distinguishable 

 by the size and shape of the aperture and of the zocecia generally. 

 It seems to be confined to the upper part of the 31. cor-testudinarium 

 zone, where it is not uncommon on the Sussex coast and may reach 

 a very considerable size, my largest specimen (a broken one) being 

 92 mm. by lS^mm. 



Pavolunulites dkclivis, sp. nov. PI. IX, Pigs. 5 and 6. 



Syn. Pavolunulites costata, Beissel, Bryozoen der Aaehner Kreidebildung, 

 p. 37, pi. iii, figs. 39-41. 

 Semieschara costata, Marsson, Bryozoen der Weissen Sehreibkreide der 

 Insel Kiigen, p. 76. 

 Non Pavolunulites costata, D'Orbigny, Paleontologie Francaise, vol. v, 

 p. 359, pi. 706, figs. 9-11. 



A form of Pavolunulites closely allied to P. scandens occurs in the 

 zone of Act. quadratus and at Trimingham. It is apparently identical 

 with the form described and figured by Beissel as P. costata, D'Orb. 

 (after comparison of his specimens with D'Orbigny's single " defective " 

 type). This identification was accepted by Marsson, but with 

 obvious misgivings, which seem justified. D'Orbigny's figure is not 

 clear enough to give details accurately, and the only substantial 

 character furnished by his description is the ribbed back, which is 

 wholly different in type from that of the Aachen and English forms. 

 The broad characters of the back are so constant among the Lunulitidse 

 that I cannot ignore this difference, and I therefore give Beissel's 

 form a separate name. There is also no sign in Beissel's figures 

 or description of the raised rim to the aperture mentioned by 

 D'Orbigny. The English specimens agree very closely with Beissel's 

 admirable figures. The species is clearly distinguished from P. scandens 

 by the longer and narrower zooecium with a sub-quadrate longitudinal 

 section (due to the steep descent of the wall from the head of the 

 zooecium to the back wall, in consequence of which it is only faintly 

 visible within the aperture), the broader and much shorter zocecial 

 aperture varying round a semicircular type and the shorter and 

 broader vibracularian aperture. P. elegems, D'Orb. (loc. cit., p. 359, 

 pi. 706, figs. 5-8), agrees very closely in the pattern of the back, but 

 is readily distinguished by the pointed zocecia. P. elegans, Beiss., 

 appears to be a different species, so named by oversight, and may be 

 known as P. Aquemis. I have not seen any definite ocecium. 



