4:06 W. A. Parks — Lepadocystis clintonensis. 



circlets of plates these ridges are radially arranged, but on the 

 upper plates this regularity is lacking. 



Pectinirhombs appear across the sutures between plates 1 and 

 5, 12 and 18, 14 and 15, and 10 and 18. Fectinirhomb 1-5 

 presents two small, oval discrete halves without apparent ster- 

 eom folds. Pectinirhomb 12-18 is larger : the half on plate 

 12 shows indistinct stereom folds, but that on 18 is almost 

 destroyed. Pectinirhomb 14-15 has a large oval half on 14, 

 presenting eight folds of stereom and lip-like margins. The 

 half on 15 is triangular in shape, with stereom folds reaching 

 to the suture and not confined by a lip. Pectinirhomb 10-15 

 has a small, oval, lipped, discrete half on 10. The portion on 

 15 is exactly the same as the other half-rhomb belonging to 

 that plate. 



The anus is large and is situated at the angle between plates 

 7, 8, 13 and 14. These plates are deeply excavated by the 

 anal margin, which is raised into an oval or circular ridge. 



Except for distinct evidence of their original presence on 

 the median line of each plate of the fourth circlet, the ambu- 

 lacral furrows are not perceptible. 



The column is round and tapers distally. The first ten 

 segments show a sharp median crest and occupy a space of 

 about 7 mm . They show a gradually increasing thickness dis- 

 tally. Beyond the tenth segment, the median crest is less 

 defined, the segments gradually becoming barrel-shaped. The 

 17th segment is 2 mm long and of about the same width. 



The present example differs from Meek's species in its 

 larger size, being 15 mm high by 10 mm wide, while the genotype 

 is ll-5 mm by 9 mm . The column, at its proximal end, is 4 mm 

 thick as compared with 3'5 mm in Meek's species. The sculp- 

 turing of the plates is different, as L. moorei shows only 

 " thread-like, radiating costse, one of which, passing from the 

 middle to each side of each plate, is usually slightly larger than 

 the others between." The shape and arrangement of the 

 plates of the cup are strikingly alike in the two species. 



Horizon — Clinton. 



Locality — Forks of the Credit River, Ontario, 



Collector — Mr. Joseph Townsend. 



Specimen number — University of Toronto Museum, No. 372 Cl. 



