ARETHUSINA KONINCKI. 83 



glabella, convex, longitudinally ovate [pointed in front], about one fifth the width 

 of the glabella, completely circumscribed by uniformly deep furrow. [Fixed checks 

 moderate, swollen, separated from glabella by deep axial furrows, and united in 

 front of it by tumid pre-glabellar portion about one fifth or sixth the length of the 

 glabella.] Facial suture curves inward from anterior margin to eye, behind which 

 it bends outward [with a slightly sigmoidal course] to cut the posterior margin far 

 out a little within the base of the spine. Free cheeks elongated, high-conical, with long 

 curved genal spines; eyes large, prominent, crescentic, smooth, situated about half- 

 way up the head and near the glabella. Occipital segment moderately broad, 

 prominent; occipital furrow strong. Border to head-shield thick, rounded, tumid, 

 as wide as neck-segment ; marginal furrow strong, but does not quite reach neck 

 furrow at base of genal spine. 



" Thorax much loss convex than head, and a little longer than it ; of eleven 

 segments; axis moderately convex, tapering quickly backward, rather wider than 

 pleurse; sixth ring much swollen and produced backward into straight horizontal 

 spine, lying upon surface of posterior rings and nearly reaching end of pygidium. 

 Pleurse short, flatfish, divided nearly to tip by strong straight central groove; 

 extremities thickened, truncate, and very faintly bilobed. Fulcrum situated about 

 halfway along pleurae of middle segments, but nearer axis posteriorly. Extra- 

 fulcral portion of pleurae sharpened and facetted anteriorly for rolling up. 



" Pygidium small, short, transverse, slightly convex, more than twice as wide 

 as long. Axis short, broad, conical, rounded, one third the width of pygidium, 

 with one distinct ring, a second less distinct, and a terminal joint. Lateral lobes 

 with fulcrum on anterior border about one third of the way out, and one distinct 

 upper furrow, not reaching the margin. All the prominent parts of the surface of 

 the body, especially head-shield, ornamented with small tubercles of fairly regular 

 size " (Salter). 



Remarks. — The only specimen of this species from the Girvan area is the one 

 in the Woodwardian Museum mentioned by M'Coy and Salter, and it is in such a 

 miserable state of preservation that its identification is doubtful, as Nicholson and 

 Etheridge remarked. 



( Collection. — Woodwardian [Sedgwick] Museum. 



Horizon and Locality. — Mulloch Hill Group (L. Llandovery) : Mulloch Quarry. 



Genus ARETHUSINA, Barrande. 

 1. Arethusina konincki, Barrande, 1846. ? Plate XI, figs. 14, 1 



184G. Arethusa konincki, Barrande, Not. pivlim., p. 48. 



1847. Aulacopleura konincki, Corda, Prodrom. Boh. Trilob., p. 84. pi. v. Bg. 4s. 

 Aulacopleura angusticevs, Corda, il>i<i., p. 85. 



