484 DR F. A. BATHEK. 



§517. Variations.— Specimens Grl74, Gl75, Gl90, and more doubtfully Gl92, 

 seem to agree with one another better than they do with Gl71 and Gl42. Not one 

 of them is well enough preserved to afford a complete comparison. Gl75 shows the 

 anal face of a theca with the proximal region of the stem. Gl74 shows either two 

 thecas, one lying over the other, or a single theca of which one side has been broken off 

 and turned over ; the main portion shows part of the antanal face on the left side, and 

 part of the anal face as viewed from within ; some proximal columnals are also seen. 

 G 190 comprises two individuals : (a) an imprint of the anal face ; (b) the proximal third 

 of a theca, viewed from the antanal face. Gl92 is a small individual, with imprints of 

 the upper part of the anal face and central region of the antanal face, but it is doubt- 

 ful whether the two fragments really belong together. 



§ 518. The points of difference from the holotype may be summarised as follows : — 



The absolute size is less ; the relative width and the shoulder-angle are greater : in 

 Gl75, width, 20 mm., height, 19 mm., ratio, r05 ; Gl74, height, 16'6mm. Shoulder- 

 angle in Gl75, circa 115°. 



The anal lobe descends to top of third flange in Gl74, to below third flange in 

 G175, to fourth flange in Gl906. 



The Pectinirhombs are not seen in Gl75 and Gl90a. They have much less 

 prominent borders and are rarely shown clearly. Rhomb 1-5 in Gl906 is almost 

 elliptical; sutural axis, ca. 2 mm.; transverse axis, ca. 4 mm.; number of folds 

 ca. 17. Rhomb 10-14 had at least 12 folds in G 174. Rhomb 11-12 had at least 10 

 folds in G175. 



The Periproctals, in Gl74, Gl75, and Gl90a, have a diameter of "9 mm. and under. 

 On the rectal lobe, which is seen from the interior in Gl74, they are elongate and 

 attached to a projecting rim. In Gl92 they are very small, '3 to "4 mm., and it is 

 doubtful whether this specimen is rightly referred here. 



The Ornament of the antanal face appears to be of the same character as in the 

 holotype, but is less prominent. In Gl92 (antanal fragment) it is, on the other hand, 

 coarse and nodular. 



The chief differences, then, are the greater relative width and the smaller size of 

 the periproctals. If one could be quite sure that the pectinirhombs agreed throughout 

 in being of different outline and structure, one might well place all these specimens in 

 an independent species. But such differences as are clearly seen may possibly be due 

 to greater youth. Therefore I retain the specimens provisionally in F. quadrata (see 

 further § 550). 



§ 519. Comparison with other Species. — The outline in the typical specimens 

 closely resembles that of P. gibha, but in that species both the upper rhombs are 

 elongate, whereas here they are widened. Further, the folds in P. quad^-ata are not 

 quite so fine and the borders of all the rhombs are not so sharp and steep. The 

 ornament is well marked in P. quadrata, but scarcely perceptible to the naked eye 

 in P. gihha. The general shape, the slightly larger periproctals, and the less narrowing 



