19(5 CONTRTBtTTIONS TO CANAT)IAN PAL.EONTOLOGY. 



oval, witli Iho leiigtli but little more than half tlie dopth, while others 

 are cii'uular, and tliOBo ma3' really pertain to a ditterent species, it' not 

 geiiuH, from the foi'mer.' In one of these scales, the depth of which 

 " is estimatetl to have been nearly '24j inches, and its length nearly IJ 

 inches," the inner poi'tion is described as exhibiting '' numerous i'adiat- 

 ing ridges, while the outer poi'tion, separated from the foi'mer by a 

 narrow, smooth tract, presents a minutely tubercular or granular 

 aspect." 



The specimens collected by Messrs. Tyrrell and Dowliag from the 

 northern continuation into Manitoba of the Cretaceous rocks of Dakota, 

 at the localities indicated, are all lai-ge detached scales, which are very 

 similar in size and shape to those described by Dr. Leidv, and which 

 do not appear to ditler from them except in some minute details of 

 their surface ornamentation. Like those from Nebraska, too, they 

 may represent more than one species, and, perhaps, even more than 

 one genus. 



Of the two specimens tigured, one (fig. 8), which measures forty-seven 

 millimetres (or nearly two inches) in depth and twenty-four mm. (or 

 about one inch) in length, is somewhat pointed above and below, while 

 its lateral margin is broadly I'ounded anteriorly and nearly straight 

 ]josteriorly. In the other, (tig. !)), which is twenty-nine millimetres 

 in depth and twenty-nine mm. and a half in length, the marginal out- 

 line is more nearly circular. When examined with a lens, the radiat- 

 ing markings on the suiface of each are seen to consist of tine grooves, 

 which are moi'e or less interrupted or broken up into rows of punctures, 

 and not of continuous raised ridges as in the types of 0. occidentals. 

 The smooth central urea is well marked in both and in all the specimens 

 collected, and the granulations on the exposed surface of each scale 

 appear undei' the lens as longitudinal but slightly divergent and 

 densely crowded rows of minute punctures with raised margins, the 

 punctures in each row being connected by a still more minute I'idge. 



ERRATA. 



Page ]](j. Immediately under the words " <iEAmmvsia akcuata ? Conrad, Var.", 

 add Plate 15, Qg. 4. 



Page I3u. Line 21 from the bottom, for " Wisaman " read VVissmaun. 



Page 138. Line 7 from the bottom, for " species " read specimens. 



Page 1U5. Between the running heading at the top and the first line below it, 

 insert the word Lameu.diranchiata. 



Page 1IJ9. Line 2 from top, for " Protocardhim Hii.lanum " read " PROTOCARniA 

 Hillana, for although Woodward, Stolickza and Tryon write the 

 name of Bey rich's genua Protooardium, yet Meek, Paul Fischer and 

 Zittel claim tliat the original siJelliiig of the word is I^rotucardia. 



