170 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxii. 



between which there are always three equally strong secondary lines. 

 Transverse, or growth, lines are fine and numerous, and in crossing the 

 longitudinal lines they cause these to be slightly nodose. 



Collector.— S. K. Carpender. Oat. No. 28L94, U.S.if.M. 



This uame is given as a mark of appreciation to Mr, Russell W. 

 Porter, of Boston, Massachusetts, who, with his associates, made it pos- 

 sible to revisit Frobisher Bay and to make a most complete collection 

 of Arctic Trenton fossils.^ 



ORTHOCERAS SCALARIFORMIS, new species. 



(Plate XII, figs. 17, 18.) 



Shellsmall, notaunulated, tapering slowly, withan apical angle of about 

 7°, section originally circular, septa 9 in the length of 1 inch ; siphuncle 

 large, and apparently in contact with the outer wall. Surface with 

 13 widely separated prominent longitudinal costoe, which are crossed 

 somewhat irregularly by concentric lamellse, anteriorly directed, and 1 

 to each septum. Here and there two or three intermediate vertical 

 lines occur between the longitudinal costae. 



Collector,— J. N. Carpender. Cat. No. 28195, U.S.N.M. 



Family CYRTOCERATID^. 

 CYRTOCERAS MANITOBENSE Whiteaves. 



Cyrtoceras manitobenfie Whiteaves, Trans. Royal Soc. of Canada, Sec. 4. VII, 

 1889, p. 80, pi. XIII, figs. 3, 4; pi. xv, fig. 4; Geol. Snrv., Canada, Pal. 

 Foss., Ill, 1897, p. 223. 



Oncoceras manitobense Clarke, Geol. Minn., Ill, Pt. 2, 1897, p. 799. 



This species is the most abundant of the Cephalopoda at Silliman's 

 Fossil Mount. The writer sent the specimens to Profe>sor Whiteaves, 

 who compared them with the types, and subsequently reported that they 

 are "apparently exactly the same species as C. manitobense Whiteaves 

 from Lake Winnepeg, Manitoba. We have very similar specimens from 

 Akpatok Island, Hudson Strait." The Baffin Land specimens are 

 smaller than those from Manitoba. 



Collectors. — J. N. Carpender, A. V. Shaw, and A. H. White. Cat. No. 

 28119, U.S.N.M. 



CYRTOCERAS CORNULUM, new species. 

 (Plate XIV, figs. 8-10.) 



This little shell is clearly related to the previous species, having many 

 of its characters. It differs, however, in its smaller growth, greater 

 curvature, and most decidedly in the very rapid increase of the cone. 

 The greater curvature is due to the rapid increase in depth of the air 

 chamber toward the ventral side, where near the living chamber it is 



' A description of this trip is given by Mr. Porter in Bull. Amer. Geog. Soc, XXX, 

 May, 1898, pp. 97-110, the paper being entitled "Frobisher Bay Revisited." 



