156 PROCEEDINGS OF THE NATIONAL MVSEUM. vol.xxii. 



BRYOZOA. 

 Family OERAMOPORIID^ Ulrich. 



CREPIPORA, species undetermined. 



Specimens of this species were sent to Mr. E. O. Ulrich, who identified 

 them as belonging to Crepipora. The minute structure, however, is 

 poorly preserved, and no thin sections were made. 



Collectors. — A. H. White, J. jST. Carpender, and A. V. Shaw. Cat. 



ISo. 28147, U.S.N.M. 



Class BRA.CE[IOT>ODA.. 



Order PROTREMATA Beeeher. 

 Family ORTHID^ Woodward. 



ORTHIS TRICENARIA Conrad. 



Orthis tricenaria Conrad, Proc. Acad. Nat. Sci. Phila., 1843, p. 333. — Winchell 

 and SCHUCHERT, Geol. Minn,, III, Pt. 1, 1893, p. 418, pi. xxxii, fig. 18-23. 



This well-known and characteristic Trenton species is represented by 

 two specimens, which are small for this form, but otherwise closely re- 

 semble those from the Galena shale of Minnesota. On Akpatok Island 

 the species attained the largest growth known, being more than three 

 times as large as those found in Baffin Land. 



Collector.— J. N. Carpender. Cat. No. 28149, U.S.N.M. One speci- 

 men was also found by Mr. R. W. Porter and is now in the American 

 Museum of Natural History. 



ORTHIS (DALMANELLA) TESTUDINARIA (Dalman). 



Orthis {Dalmanella) testudinaria Winchell and Schuchert, Geol, Minn., Ill, 

 Pt. 2, 1893, p. 441, pi. XXXIII, figs. 17-22. 



This ubiquitous Lower Silurian species is very abundant at Silliman's 

 Fossil Mount, and at this locality is quite constant in its characters. 

 The specimens belong to the variety with fine striae, in which the dorsal 

 valve is often slightly convex, recalling the subgenus EMpidomella 

 rather than Dalmanella. However, other examples have the typical 

 flat dorsal valve, with a well-defined median sinus. 



Collectors. — J. N. Carpender, A. H. White, and A. V. Shaw. Cat. 

 No. 28148, U.S.N.M. The American Museum of Natural History also 

 has a number of specimens collected by Mr. E. W. Porter. 



ORTHIS (PLECTORTHIS) PLICATELLA Hall. 



OrtMs (PlectortMs) pUcatella Winchell and Schuchert, Geol. Minn., Ill, 

 Pt. 1, 1893, p. 436, pi. xxxiii, figs. 5-7. 



As a rule, this species is not abundant in the Trenton either in New 

 York or in Minnesota, but at Silliman's Fossil Mount it is a common shell. 



