Page:TransRoySocCanada 16 4 159-167.djvu/6

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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, semiovate, 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.)