OARADOCIAN CYSTIDEA FROM GIRVAN. 489 



anal face, along the axis of the lobe ; hence it is always greater than the distance 

 below the stem -facet, which is measured parallel to the stem. The difference is less 

 in such a species as this, where plate 3 is bent vertically downwards, than in a species 

 where the bend is less. 



§ 542. The Pectinirhombs are all very well developed and provided with a raised 

 border, sharp on the adcentral side of the rhomb and rising in a concave curve from 

 the surface of the plates, more rounded on the other side of the rhomb. 



Pectinirhomb 1-5 is almost square in Gl89 and G 135, but apparently more trapezoid 

 in G213. The number of folds seems to be about 10 in Gl89, and about 12 in the 

 two other specimens. 



§ 543. Pectinirhomb 10-14 is almost regularly kite-shaped, the obtuse angle being 

 uppermost and the half of the rhomb on plate 14 being a trifle the larger. 



In Gl89 (text-fig. 74) the sutural axis is 5 mm., the transverse 2*8 mm., the 

 number of folds about 25, those on plate 14 being partly covered by epistereom. In 

 Gl35 (text-fig. 75) the axes are 4*2 mm. x3 mm., the folds about 

 20, very slightly covered. In G213 the actual measurements are 

 5*5 ram. x 2'5 mm., but the latter has apparently been reduced by 

 some shifting of the plates, so that I estimate the ratio as "5 rather 

 than "45 ; the number of folds is about 25, closed, if at all, only 

 near the outer angle. In Gl70 the measurements are approximately text-fig. so.- PZmro- 

 4-8 mm. x 4-6 mm., and the number of folds about 18 ; with so low cystis forioius. Pec 



' ' timrhomb 11-12, m 



a number of folds a greater relative width is only natural, but the specimen G223. x 5 

 apparent width is in this case increased through being observed on 

 the inner face of the rhomb where the folds always stretch further than they do 

 on the outer face. Therefore the ratio '96 is probably too high. The facts may 

 fairly be summarised by saying that in a normal form this rhomb has about 

 22 folds, a width about three-quarters of its length, and that it is placed near the 

 lower end of the suture. 



§544. Pectinirhomb 11-12 (text-fig. 80) is trapezoidal, approaching square, but 

 slightly wider across the suture as a rule, has 10 or 11 folds, occupies less than one- 

 third of the suture, and is placed a little more than half-way down the suture. So 

 far as can be seen, the folds are regular and uncovered. 



§545. The Periproct is wide. Plates 12 and 14 are widely separated in Gl89 

 and, apparently, in G213, but perhaps not quite so widely in G223. 



§ 546. The Periproctals have a diameter of about "4 mm. in Gl89, not more than 

 ■4 mm. in G135, about '5 mm. in G213, about "65 in G216, and some attain as 

 much as 7 mm. in Gl70, and even "9 mm. in G223. Those on the rectal lobe do not 

 appear specially elongate. 



The Vent is not clearly seen. 



§ 547. The Ornament of the antanal face is most marked in G213 (PI. VI. fig. 77), 

 where the granules form fine but clear rhombic and radiate ridges ; the concentric 



