164 THE ROYAL SOCIETY OF CANADA 



when one considers the shape of the carapace, its ornamentation, the size 

 of its marginal spines, and the faint representation of the median keel 

 behind the cervical furrow. Woodward's figures of A . grossarti, unlike 

 Salter's, show the cervical furrow quite distinctly, and a median 

 keel precisely like that of A. hillianus. I retain the Nova Scotian 

 species since it has a stronger curvature fore and aft of the lateral 

 margins of the carapace. Thus, in the Inverness specimen, the antero- 

 lateral angle formed by the anterior and lateral margins (neglecting 

 the acute spine) is roughly 120° as compared with 110° in A. grossarti, 

 too great a difference to be due to pressure. A . dubius, on the contrary, 

 is readily distinguished by the absence of marked antero-lateral 

 spines, the arcuate frontal margin, and the even, pronounced, strength 

 of the median keel which runs to the posterior margin. 



Class Arachnida 



Subclass Merostomata 



Eurypterus {Anthraconectes) brasdorensis n. sp. 



Description: (Based on a single carapace.) Carapace, semi- 

 ovate, with length nearly three-fourths the maximum breadth. The 

 posterior margin very slightly convex backwards. Genal angles 

 produced into short bluntly acute spines. Between the prominent 

 reniform compound eyes there is a pair of elongate elevations which 

 border a median depression in which lies a circular ocellar mound 1.3 

 mm. in diameter. This mound is situated directly in front of a line 

 tangential to the posterior borders of the eyes and was apparently the 

 seat of the ocelli. A second pair of elevations run obliquely from the 

 middle of the posterior border towards the lateral margins, so that 

 the eyes are situated in triangular, depressed areas of the test. 



The surface is marked by raised scales or mucros on a finer 

 shagreen ground. The individual outline of these scales is hemioval 

 to hemispherical with their flat slopes facing anteriorly. In the 

 posterior half of the shield, except in the depressed areas, the mucros 

 are large, raised, more acutely pointed, and plainly visible to the 

 unaided eye. Anteriorly and in the depressions, they are fine or 

 microscopic, with much less relief. Adjacent to the lateral margins 

 they become greatly elongated and flattened, and either border the 

 margins in a parallel position or meet them obliquely at very acute 

 angles. Anteriorly, the carapace is clearly folded underneath in a 

 doublure and a faint, narrow, V-shaped ridge, situated medially close 

 to the anterior margin, is probably due to the pressure from the ventral 

 border of this fold. (Compare A. kidstoni.) 



