51 



Dendrocrtnus Jewettii. — Billings, 18o9. 



Mr. W. R. Smith has kindly allowed me to examine a very hand- 

 some series of specimens of this species collected by him from the Tren- 

 ton limestone at Belleville, where Col. Jewett discovei-ed the fragment 

 upon which the species was founded. Mr. Smith's are the only speci- 

 mens of this I'are species now in Canada, and they show many new 

 points of interest. 



The type specimen wnnted the arras, but these specimens have 

 them well preserved. An stated in the original description, each of the 

 primary rays consists of one large plate, included in the cup, and four 

 smaller plates above. We now learn further that the secondary rays 

 ai'e each composed of four pieces, the tertiary of seven, the quaternary 

 of six or eight (they appear variable), while two portions of quinary 

 rays have IG and 18 respectively. Thus this crinoid has at least forty 

 arms. 



Amygdalocystites. — Billings. 



This genus was founded in 1854. In describing it the author 

 iuA'ariably stated that the plates were solid or non-poriferous. 



In the Trenton limestone at Hull, I collected a specimen agreeing 

 with A. florealis, excepting that it is smaller than the type specimen and 

 has smooth plates ; this specimen lias a poriferous test. The pores are 

 circular and arranged on the sutures, half a pore being on one plate and 

 the remainder on the plate contiguous, and there are as many half pores 

 or sulci to each plate as it has sides, the sulci being subcentrally situ- 

 ated on the sutures. On examining the type specimens of A. Jloredlis 

 in the G. S. C. Museum, I found the pores distributed [)recisely as I 

 have stated, i.e., one to each suture, but Mr. H. M. Ami, who at my 

 request kindly inspected the types, found on one a plate near the 

 base bearing a double quantity of sulci. The type specimens of J. 

 tenuiradiatus were not sufficiently well preserved to show the pores, if 

 such existed. I discovered that the type specimen of A. radiatus had 

 on each suture two pores near the angles and close to the ends of the 

 radiating ridges, the adjacent pores of three contiguous plates forming a 

 group. 



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