112 The Ottawa Naturalist [December 



consisted of a more or less flattened expansion of small area, with a 

 tendency toward radicular extensions at the margin, similar to the form 

 of attachment of certain crinoid columns. 



28. Acknowledgments. -The present paper could not have been 

 written without the assistance of numerous individuals. The writer is 

 under great obligation to the Director of the Geological Survey of 

 Canada not only for the privilege of examining all of the specimens of 

 Comarocystites punctatus preserved in the Victoria Memorial Museum 

 at Ottawa, including the Billings types and the remarkable complete 

 specimen presented to the Museum by Sir James Grant, but also for the 

 excellent photograph of this complete specimen and for the enlarged 

 photograph of that one of the Billings types preserving the pinnulate 

 arm, here reproduced. To Mr. James E. Narraway and Mr. Walter 

 Billings he owes not only the loan of the specimens figured on plate II, 

 but also the use of other specimens, and valuable notes on the distribu- 

 tion of this species in the Ottawa area. 



The types of Comarocystites shumardi and its so-called variety 

 obconicus belong to the Worth en collection at the University of Illinois, 

 and were loaned by Prof. T. E. Savage. The type of Comarocystites 

 shumardi is here figured. Of the specimens of Comarocystites shumardi 

 in the Walker Museum, at Chicago University, loaned by Prof. Stuart 

 Weller, two are here figured. Of two specimens of the same species, 

 belonging to the Illinois State Museum of Natural History, at Spring- 

 field, loaned by the curator- Dr- A. R. Crook, one is here figured. 



The arm bearing specimens of Caryocrinites ornatus, preserving 

 the pinnules, in the U. S. National Museum, at Washington, were 

 placed at the disposal of the writer by Mr. Frank Springer, to whose 

 collection they belong; and to his assistant, Mr. Herrick E. Wilson, the 

 writer owes the excellent photographs of the pinnulate arms here repro- 

 duced. To all of these named the writer wishes to acknowledge the 

 favors freely granted and gratefully received. 



plate IV. 

 Fig. 1. Comarocystites shumardi, Meek and Worthen. Specimens No. 

 10974, belonging to Walker Museum, at Chicago University. A, anterior view 

 of theca, specimen tilted so as to show the peristomial plates along the 

 anterior side of the apical transverse food-groove. The quadrangular plate 

 and the more pentagonal plate on its left margin correspond to the plates 

 marked a, a, in the diagrams of Comarocystites punctatus. The mouth is 

 situated at the posterior end of the suture between these plates. The branch- 

 ing of the transverse apical food-groove is indicated on the proximal side of 

 the left stereom protuberance. The cavity occupied by the anal pyramid is 

 seen on the left side of the figure. On the right side of the figure, the theca 

 is defective. B, right side of same specimen, tilted so as to show the anal 

 opening and the immediately adjacent thecal plates. For diagrammatic pur- 

 poses the stellate grooving of the thecal plates has been accentuated and the 

 remote (left) end of the apical transverse food-groove is represented as 

 branched, although the specimen here is too imperfect to show this branching. 

 C, posterior view of a second specimen, tilted so as to show the thecal plates 

 on the posterior side of the transverse apical food-groove. The plate posterior 

 to the middle of this apical food-groove corresponds to the plate marked rp 

 in the diagrams of Comarocystites punctatus. From this plate the linear 

 hydropore passes diagonally downward and toward the right, across the 



