474 T>R F. A. BATHER. 



very distinct, somewhat wavy, granular ridges, parallel to the margins, but some- 

 times (as in the Oxford specimen) crossing the sutures. The periproctals also are 

 finely granular, and this feature is well marked in the Oxford example. 



§ 461. It is not clear to what Salter was referring when he said that the holotype 

 showed part of one of the Arms. The object shown near the top right-hand corner of 

 his figure appears to have been intended for the impression of a distal part of a stem, 

 which, however, does not exist. The arms of the specimen, if present at all, are buried 

 in the matrix. 



§ 462. The Stem in the main individual retains about 22 columnals, which make 

 up a total length of 28 mm. in an almost straight line. The distal end is not shown. 

 The columnals have a greatest diameter on the flange in the proximal region of 

 5 "6 mm., and from this taper gradually to 1"9 mm. in the distalmost preserved. The 

 interval between the bottom of the proximal flange and the bottom of the next is 

 about 1 mm. In the distal region the corresponding interval is about 17 mm. The 

 flanges are ornamented with granules arranged in irregular vertical ridges. The 

 intermediate columnals are also slightly granular, and in the distal region their granules 

 form a transverse annular ridge half-way down the ossicle, corresponding to the ridge 

 formed by the flange in the other ossicles. In addition to these annular swellings the 

 ossicles may be covered with very fine transverse ridges of granules, and crossing these 

 are broad vertical folds or furrows, giving somewhat the appearance of wickerwork. 

 This is well shown by an isolated columnal in specimen 7434. 



§ 463. Comparison with other Species. — With P. anglica[\ 485), with P. procera 

 (§ 500), with P. gibba (§ 534). See also the Key (§ 551) and the comparison with 

 American species (§§ 552, 553). 



§ 464. Pleurocystis anglica. 

 (Plate V. figs. 60-62. Text-fig. 70.) 



1899. Pleurocystites Rugeri Salter, 0. Jaekbl, " Stammesgesch. d. Pelmat.," p. 130. 

 1899. Pleurocystites anglicus, 0. Jaekbl, op. cit., p. 235, pi. 12, ff. 6, 6a. 



§ 465. Diagnosis. — A Pleurocystis of elongate trapezoid outline, the sides sloping 

 gently upwards and inwards from the umbones of plates 7 and 8 to the level of the rhombs 

 on ] 2 and 14, at an angle of circa 40° [then probably sloping towards each other at circa 

 90°] ; ratio, width : height, of theca [unknown, calculated as about] -8 ; of plate 5, 1*15 ; 

 plate 3 descends to probably between second and third flange. Pectinirhombs all 

 present, with raised border ; all widened, long-elliptical ; [ratio of axes uncertain] ; folds 

 uncovered. [Upper limits of periproct unknown, but it is clear that] plates 12 and 14 

 do not meet. Diameter of periproctals ranges from 1 mm and less in middle region 

 to '3 near margin. Ornament of antanal face, granules in concentric lines, and in main 

 axial and rhomb ridges, and radiate ridges. Columnal flanges bear prominent granules, 

 which may be in vertical series. 



