146 



ATHYRIS JULIA. (N. sp.) 

 6 



Fig. 124. 

 Fig. 124. JLthyris Julia, a, dorsal, 6, side, and c, ventral view. 



Description. Shell of medium size, moderately convex, subovate' 

 greatest width a little in front of the middle ; sides rounded ; front margin 

 truncated ; apical angle about 90 ; cardinal slopes straight for nearly one 

 third the length of the shell. Ventral valve moderately convex, most 

 elevated about the middle, thence uniformly arched to the beak, more 

 abruptly curved to the front margin. Umbo small, prominent; beak 

 pointed, incurved over the hinge-line, but not in contact with the umbo of 

 the dorsal valve ; a wide, flat, shallow mesial sinus which indents the ante- 

 rior one fourth. Dorsal valve uniformly convex all over except a short 

 flat mesial elevation in front. Surface with a smooth polished aspect, but 

 when closely examined exhibiting numerous obscure concentric striae. 



Length of specimen 7 lines ; width the same ; depth of both valves 

 5 lines. 



Locality and Formation. The Jumpers, Anticosti. In Division 4, 

 Anticosti group ; Middle Silurian. 



Collector. J. Richardson. 



The following species with its varieties are referred to the genus 

 Aihyris provisionally. The shell structure resembles that of Atrypa reti- 

 culariS) but the muscular impressions are more like those of Athyris than 

 those of Atrypa. In some polished sections I have detected traces of 

 internal spiral appendages, but have not ascertained their position. Should 

 it be found that they are situated as in Atrypa, it may become necessary 

 to refer this species to that genus. The fossil called (by Prof. Hall) 

 Orthis erratica belongs to the same group, and so do, most probably, 

 Rhynchonella modest a and R. recurvirostra. 



