608 THE UPPER SILURIAN. 



lose. The specimens are not sufficient to make any satisfactory 

 determinations regarding specific differences. Arisaig, East River. 



Dalmania Logani, Hall (Fig. 215). The specimens are two or 

 three imperfect cephalic shields, one preserving the palpebral lobes, 

 and others consisting principally of the glabella, with two or three 

 parts of caudal shields. There is a fragment of a cheek which may 

 be of this species. Cephalic shield somewhat semicircular. Glabella 

 ovate, wider in front and truncate behind, depressed convex ; occipital 

 ring narrow, prominent ; occipital furrow bending a little forward in 

 the middle, and curving gently backward in the middle of each side, 

 and again turning forward ; posterior furrows narrow and sharply 

 impressed, each one extending about one-third across the glabella and 

 curving forward at their outer extremities ; central furrow linear, 

 obscure, having a direction transverse to the axis ; anterior furrow 

 obscure ; oblique to the axis, linear extending to the margin of the 

 glabella a little forward of the eye ; frontal lobe regularly rounded 

 anteriorly. A fragment of a cheek in the same association is broad, 

 produced posteriorly in a short strong spine, and marked by a broad 

 sub-marginal groove. Caudal shield somewhat semi-elliptical, convex, 

 acute behind, axis very prominent, rounded and marked by about 

 eight annulations, which are gently curved backward at the extremi- 

 ties ; lateral lobes with six simple flattened ribs which terminate in 

 a thickened border, and separated from the axis by a strongly defined 

 furrow ; extremity abruptly pointed. 



The glabella of this species more nearly resembles Phacops in the 

 general form and faintly impressed furrows, of which the posterior 

 one is conspicuous. The form of the palpebral lobe, and the absence 

 of tubercles at the base of the glabella, together with the form of the 

 caudal shield, ally it with Dalmania, and it may be compared with 

 D. Phillipsi of Barrande, but has a more pointed caudal shield, and 

 the cheek, if correctly referred, is prolonged in a posterior spine 

 Arisaig, coll. J. W. D. 



Proetus Stokesii (?), Edwards. Arisaig, coll. J. W. D. 



Homalonotus Knightii, Konig. Arisaig, Dr Honeyman, 



Phacops Downingii, Salter. Arisaig, Dr Honeyman. The two 

 last species are given on the authority of Dr Honeyman's and Mr 

 Salter's lists. 



Beyrichia pustulosa, Hall (Fig. 216). Valves unequally semi- 

 oval, a little more than once and a half as long as wide ; surface 

 marked by three prominent ridges ; central, anterior, and posterior. 

 The central one is a single oblong oval tubercle, which is directly 



* Attached to a fragment of one of these trilobites is a small Spirorhis. It is dextral, 

 with two to three turns, and rounded concentric wrinkles on the last whorl. — J. W. D. 



* 



