408 CONTRIBUTIONS TO CANADIAN PALEONTOLOGY. 



sutures is so irregular in outline as to be evidentl)^ due to minute imper- 

 fections or breaks in the casts of tlie interior, or of the shell wall of these 

 chambers. 



This little pyritized Bartri/px is abundant at Bartlett's Mills, but not 

 quite so common at Thedford. At both of these localities specimens were 

 collected by the Rev. Hector Currie in 1882, and more recently by 

 Messrs. Kernahan, Schuchert, Walker and others. Altogether the writer 

 has seen nearly a hundred of these specimens, the largest of which are 

 not quite an inch long. Some of them are casts of the interior of the 

 body chamber, either alone, or with one, two or more of the air chambers 

 attached. In such specimens the body chamber is from nineteen to 

 twenty-three millimetres long, and its dorso-ventral diameter anteriorly 

 averages five mm. Others are casts of considerable portions of the 

 septate end of the shell, sometimes with a small piece of that of the body 

 chamber, and in one of the former fourteen septa can be counted in a 

 fragment that is a little over fifteen nnn in length. Figure IT) on Plate 

 48 is a composite drawing, the body chamber being drawn from one 

 spc(.:imen and the septate portion from another. 



Nepiiriticeras liratus. Hall. (Sp.) 



l/,in^.'rnix liniliu,,, Hall. ISCd. Tliirt,.',.iith \U-p. y. Y. St. (':ili. Nat. Hist., ]i. 10-t. 



1S7I). lllnstr. Dc'ViM.iaii Fossils : CVphaluiinda, pi. r.T, figp. 5, 



C : pi. fiS, Hh's. 1, 2; anil j.l. (Ill, ti^s. S, !l. 

 Ninitiriix llr.ilvx. Hall. 1S7!). I'al. N. ^■(.rk, Vol. V., |it. 13, p. ^107, pi. .^7, fi^js. ?, ; and 

 pi. GO, fis's. S and II. 



Two imp?rfect and badly picserved nautiloid shells in the JIuseum of 

 the Survey, collected in the Tounsliip of Bosan(piet, by Mr. I'ettit, in 1868, 

 seem to represcMit a form of this specic^-^ in which the spiral ribs are rather 

 more numerous thnn usual. One of these, a cast of tlie interior of the 

 five la-it air chamliers and of a considerable portion of the chamlxM- of 

 habitation, about 100 millimetres in length and about si.Kty-three in 

 breadth at the apirture, has fi-om thirty-tivc to forty spiral ribs. The 

 other, which is a <listorted cast of the chamber of habit.ation of a much 

 larger specimen, about 141 miliimetre.s in length and 10.". mm. in breadth 

 at the aperture, shows no indication of any ribs. 



In his latest desiaiption of N. /i.ratiis, Hall says that in the typical 

 specimen there are "fourteen I'evolving ri<lges over the chambered portion 

 of the shell," and th.it in another specimen there are "nine strong 

 plications soen on the lateral face of a partially compivssod gr-and cham- 

 ber." r.ut, in the specimen of X. lirafiis repre.s(^nted by fig. 9 of Plate 

 GO of the second part of th(^ fifth volume of tlu^ Pal.'contology of the 

 Stat(! of New York, as many as fifteen ribs can be counted in one half 

 of the circumference. 



