OARADOCIAN CYSTIDEA FROM GIRVAN. 



449 



Upper Lyckholm, but the Lyckholm Beds do not extend to within a hundred miles 

 of St. Petersburg. 



§ 341. Material. — Specimen G214, consisting of a fragmentary imprint with the 

 imperfect internal cast. 



S 342. Description. — The accompanying diagram shows the plates so far as their 

 outlines can be deciphered. I am quite unable to identify the plates with certainty, 

 but, since there is no trace of the periproct. 1 suppose that they belong to the anterior 

 region. The plates seem to lie above one another, somewhat as in Glyptocystis, rather 

 than to alternate, and this may be due to the upward passage of some plates from 

 Circlet II. 



§ 343. The measurements of the internal cast are : height, 32 "3 mm. ; diameters, 

 19 mm. and 9 mm. The theca cannot well have been less than 35 mm. high, and was 

 at least 22 mm. wide at the level of Circlet IV. in the crushed fossil. 



Circlet IV. 



Circlet III. 



Text-fig. 59. —Diagrammatic interpretation of the specimen of Cheirocrinus interrupts, G 214. 

 X 2 diameters. Of. PI. IV. fig. 48. 



The best preserved plate in Circlet IV. measures : diameter above, 6 '7 mm. ; 

 diameter below, ca. 10 mm. ; length of long side, 15 mm. ; length of short side, 

 ca. 1 1 mm. 



§ 344. A fine granular ornament is very distinct on those parts of the plates in 

 Circlet IV. that are below the subvective grooves. In the lower part of the theca the 

 ornament is finer, with some tendency to run in lines as in C. constrictus, but coarser 

 than in that species. 



§ 345. Each half of the large pectinirhomb in Circlet IV., in the middle of the 

 diagram, is traversed by about seven bridges dividing up the transverse folds. The 

 number of folds is about sixty-five. Their continuity is less interrupted on the interior. 



§ 346. The number of pectinirhombs is unusually large, there being one on every 

 suture. Along the lower margins of the large plate in Circlet III. there appear to be 

 three rhombs. This, perhaps, need not necessarily imply that the plate rests on three 

 plates of Circlet II., if we suppose that the rhomb on the right-hand lower margin 



