236 



There is no question that in the Canadian form three rings, of the five 

 that are strongly marked, are still a part of the pygidium ; but if they 

 were free rings there would be a remarkably close assimilation to Cono- 

 phrys, the difference being only in the greater number of rings in the 

 thorax of this genus. Looked upon as a developmental stage of Asa- 

 phellus this difference is to be expected, as our form is smaller than 

 Conophrys Salopiensis. 



The differences in the headshield are also of a kind that naturally follow 

 from the two being different stages of development. Dr. Callaway shows 

 the front lobe of the glabella as much more distinct than that of the 

 Canadian form, though he speaks of it as being " hardly distinguishable 

 from the front of the head;" in the Canadian form this lobe is barely 

 discernable, except at the sides of the glabella. Again he speaks of the 

 neck furrow being "deep," whereas in the Canadian form it cannot be 

 discerned, and the lateral furrows are fainter and more embryo-like. 

 Conophrys Salopiensis therefore may very well stand as a developmental 

 stage of A. Homfrayi, somewhat more advanced than the youngest form 

 ascribed to this species from the Canadian beds. The development of 

 one genus from another in the earliest larval stages is shown in the obser- 

 vations on the development of Anomocare stenetoides from an Olenus-like 

 (Acantholenus) larva.* 



^ n tne other hand, those studies show that Conophyrs or rather Shu- 



ment in mardia may be a valid genus, arrested in the phvlum from which Asa- 



Bathyuriscus 



and Anomo- phellus and Asaphus were elaborated ; if so, however, we should be able 



to find it in faunas from which these genera are absent. Nevertheless it is 

 quite possible that it might be absent from faunas which have the later Asa- 

 phi, if the Shumardia stage were passed over in the development of the later 

 forms of this family. Such a case of arrested development, and fixation 

 of larva! as specific characters, seems to be presented to us in the species 

 Bathyuriscus pupa of Mt. Stephen fauna, f as well as in Acantholenus 

 spiniger.* 



That the form which we have described as an early moult of Asaphellus 

 Homjrayi is Asaphoid, though so far removed from the adult in form, I 

 think is shown by its peculiar glabella, fading away at the front into the 

 frontal area of the cheeks, so that the line of demarkation between the 

 two is not clearly traceable, a very common character in the Asaphoid 

 trilobites. In this form it appears to the writer that the faint crescentic 

 lobe in the front of the glabella is homologous with the front lobe of the 

 glabella and the eyelobes collectively, and that the flaring anterior ends 



* Bull. Nat. Hist. New Brunswick St. John, 1898, No. xvi, p. 40. 



