EARLY DEVOXIC HISTORY OF NEW YORK AND EASTERN NORTH AMERICA 239 



On the brachial valve a fold to correspond to the obscure median sinus of the pedicle 

 valve is not always to bo seen. So far as observed, the multiplication of the striae of this 

 valve seems to be wholly by bifurcation. With respect to their interior characters, both 

 valves present normal structure with a considerable development of the median septum in 

 the pedicle valve. 



The Gaspe sandstones afford in some abundance a series of shells 

 among which we observe that the smaller members express clearly and fully 

 the features of C h. h u d s o n i c u s. It is unnecessary to further 

 characterize these individuals except to add that (i) they, like the larger 

 shells, seldom reveal any evidence of cardinal spines which are likewise 

 seldom, seen in C h. h u d s o n i c u s, and (2) it is possible to detect in them 

 faint indications of crenulatiorts along the hinge of the pedicle valve, a 

 feature which has not been noted in the Becraft mountain shells and which 

 even here would hardly excite attention were it not for its manifest relation 

 to more striking development in associated shells. These smaller shells 

 having clearly all the characters of C h. h u d s o n i c u s definitely restrict 

 the application of this term in this series of Chonetes. 



It is evident however that the limit of specialization expressed by the 

 New York shell is far overpassed in the Gaspe series. By the most gradual 

 development accompanied by an apparently regular increase in size the 

 shells attain differentials not apparent in the C h. h u d s o n i c u s stage. 

 These differences are seen in the slow but eventual alteration of outline 

 from a transverse to a more elongate form, accompanied as already stated, 

 by concomitant increase of size; in the strong development of the cardinal 

 denticulations. At the same time there is no deviation in contour or orna- 

 ment of the exterior. To the denticulations of the hinge line special atten- 

 tion may be directed. In the eventual or terminal expression of this feature 

 we find this denticulation to consist of stout, strong processes, free at their 

 extremities, largest near the deltidium and running almost, if not quite, to 

 the cardinal extremities. The upper part of the cardinal area remains 

 smooth, the denticulations terminating rather abruptly at or close to the 

 hinge line. This is a structure altogether similar to that in Stropheodonta 

 and its immediate allies, and in this instance has no apparent connection 

 with the cardinal spines or spine tubes. We have observed that the only 

 evidences of spines present in the Ch. hudsonicus stage are occasional 

 blunt bases or tube fillings and in the larger shells even these have been 

 found wanting. 



We are presented in this case with a most forcible example of a species 

 in one marine province passing beyond the limitation of ontogenic develop- 

 ment acquired by that of another. The former is the whole of which the 

 described and delimited latter is relatively but a part though complete in 

 itself. To express the former in terms of the already delimited species we 

 propose to apply the term h u d s o n i c u s as above used, to that portion of 



