24 



CRUSTACEA. 



Genus Asaphus, Brono-niart. 



Fig. 7. 

 Fig. 7. — Asaphus platyeephalus, from English Head. 



A. PLATYCEPHALUS, Stokes. — Occurs in numerous localities on the north 

 side and west end of the island. It is not easy to distinguish fragments of 

 this species from such forms as A. canalis, A. megistos, and some others. 

 We have, however, from English Head, a specimen with the head and the 

 first six segments of the body perfectly preserved with the posterior angles 

 of the cheeks clearly developed. I believe, also, that some detached pygidia 

 from Gamache Bay in Div. 1, A. G., belong to this species. 



A. NOTANS, n. sp. — Form ovate, broadly rounded at both extremities, 

 pygidium obscurely trilobed, cheeks terminating in small spines. Head 

 strongly convex, semi-elhptical or rather lunate uniformly rounded in front, 

 the margin from a line crossing a little in front of the eye backwards to 

 the points of the spines somewhat straight but sloping outwards. Eyes 

 about one-third the whole length of the head and so situated that a hne 

 drawn across the head at the mid-length would touch their anterior angles. 

 The terminal spines are acutely sub-conical, rounded on the inner side 

 and with, apparently, a sharp edge on the outside ; they extend backwards 

 to about the third pleura. Length of the head from the front to posterior 

 margins in a straight line (or by callipers) a little less than half the width 

 at the posterior margin and also about one-eighth less than the length of 

 the thorax. The latter is distinctly trilobed, the axis moderately and 

 uniformly convex and a little more than one-third the whole width. Pyg- 

 idium moderately and uniformly convex, nearly a semicircle, its length a 

 little more than half its width ; no concave groove round the margin ; the 



