R. 31. Brydone— Further Notes on the Trimmingham Chalk, 297 



avicularia develop very decided beaks, connected by a thin, almost 

 horizontal plate into a barrier right across the cell which overhangs 

 and entirely conceals the primary aperture, while even the area 

 between the primary aperture and the ovicell is now so deep set as 

 to be visible only in special liglits. It is the rule for every cell to 

 attain this stage, but the fragility of the plate between the avicularia 

 produces many variations in the shape of the secondary aperture 

 when the specimen is handled at all roughly. CeUepora pinguis, 

 Hag., appears to be a relation. 



Ckibrilina DiBLEYi, sp. nov, (Fig. 8.) 

 Colony always adherent. Cell elongated. Aperture heel-shaped, 

 surrounded by a flat raised margin, the lower lip being triangular, 

 with the apex directed down the front wall. The upper lip bears 

 four or five hollow denticles (when there are five the fifth is a small 

 one between the two at the head of the cell). Ovicell large and 

 globose, witli faint radial markings, and covers the two (or three) 

 upper denticles. Front wall marked by about 17 lines of fine 



Fig. 8. 



pores, increasing slightly in size towards the margin. These lines 

 do not (except the topmost pair) meet in the middle, but leave an 

 imperforate bar down the centre. Nearly every cell has one 

 avicularium, many have two. They are either mandibular and 

 slender, with thin marginal walls connected by a slender rod near 

 the base, or broadly oval. The latter are probably decayed or worn 

 specimens. 



Cribrilina Jukes-Brownei, sp. nov. (Fig. 9.) 

 Colony always adherent, generally growing in narrow ribbons. 

 Cell based on a primitive form like Beptescharella incequalis, D'Orb., 

 but with a decided rim. It has a long globose ovicell, up the front 

 of which two slender ridges run diagonally from each corner of the 

 aperture, meeting in an angle at nearly the highest point of the 

 ovicell. The lower lip of the aperture is produced forwards and 

 upwards into a broad band in three sections. The lowest of these is 

 bluntly triangular, with the apex pointing downwards. At the sides 

 of the cell it rises gently to the second section, which is, however, 

 strongly arched in the middle, and so leaves there an opening 

 between it and the first section. The third section is at a higher 

 level still, more or less flattened and buttressed, apparently not 

 against the side walls but against two lateral tubes (presumably 



