96 ROYAL SOCIETY OF CANADA 
OBOLUS PRISTINUS (Plate 1, fig. 8). 
Nearly cotemporaneous with the last is a somewhat larger species, 
which, if the markings are interpreted aright, has similarly advanced 
centrals in the ventral valve, but the anterior adductors of the dorsal 
are unusually far back. This is counterbalanced by the position of 
the “7” laterals which are only } of the length of the valve from 
the front. The surface markings are fine and more like later than 
earlier species. 
The Paradoxides beds, though containing a varied fauna and 
several genera of Brachiopoda, shows hardly a single example of 
Opolus; this is especially true of the Lower Paradoxides beds, where 
the bulk of the fauna is found. 
Ogozus ELLA (Plate 1, fig. 9). 
This form, formerly referred to Lingulella, is decidedly Oboloid 
in shape. It differs from the type lin the backward position of the 
“7” laterals of the dorsal valve; also the anterior adductors of this 
valve are set further back than in ©. Apollonis. Mr. Walcott’s refer- 
ence of it to Westonia would also indicate that the sculpturing of the 
surface of the valves differs from that of Eichwald’s species. 
OBOLUS REFULGENS (Plate 1, fig. 11). 
This species is very near the geological horizon of Obolus Apollonis, 
but lived in a different habitat. The latter species abounded in sand- 
stone beds, but the former in fine dark gray shales or mud-beds. Being 
very thin, the internal markings of the valves of O. refulgens are faint, 
and it is only lately that specimens have been found which show that it 
is not a typical Obolus. In Obolus proper (Euobolus) the scars of the 
anterior adductors of the dorsal valve are separated far from each 
other, but in this species they are closely approximated; they are 
closer together than those of Lingulella, and are parallelled only by 
those of Monobolina, Salter. Lingulella Davisii, which is nearly co- 
temporary with these two forms, is intermediate between them as 
regards the approximation of these two muscle scars. 
From an examination of the internal features of the valves of 
the several species of Obolus, which the author has briefly outlined 
above, the reference of these species to that genus, taking O. Apollonis 
