44 TRILOBITES OF GIRVAN. 



Remarks. — A few more additions to our knowledge of this peculiar trilobite can 

 be made by means of Mrs. Gray's specimens. In one head-shield (PI. IV, fig. 13), 

 there is a small median tubercle on the glabella a little behind the posterior pair 

 of pits, which are connected by a pair of short curved furrows with the posterior 

 margin ; the narrow pre-glabellar area is crossed by 5 — 6 distinct rugae on each 

 side with a smooth median space between the two sets ; and there seem to be 2 — 3 

 fine raised lines or nervures radiating backwards over the cheek from the side 

 of the glabella opposite the anterior pair of pits. No trace of free cheeks is 

 preserved. The characteristic lineation on the neck segment behind the fixed 

 cheeks is well preserved. 



In another specimen (PI. IV, fig 14) we see a nearly complete individual, the 

 head only being imperfect anteriorly. The thorax shows six or seven segments, 

 and the axis gradually tapers posteriorly. Nicholson and Etheridge remarked 

 that there were at least six thoracic segments ; and they also noticed the fine 

 raised oblique lines crossing the grooved pleuras, which are well shown in this 

 specimen. The semicircular pygidium, of which Wyville Thomson only had a 

 fragment for description, shows a tapering axis of 10 — 12 rings, of which the first 

 4 — -5 show an obscure trilobation ; the lateral lobes possess a half -pleura on the 

 front edge followed by 6 — 7 pairs of complete simple unfurrowed pleurae 

 reaching the raised angular border and separated by strong interpleural furrows 

 from one another. Only the first four pairs of pleura? correspond with the axial 

 rings. 



Affinities. — The true relations of this genus have always been difficult to decide. 

 Wyville Thomson (op. tit .) was inclined to regard it as intermediate between 

 Trinucleas and some of the Olenidge. With regard to the head-shield the affinity 

 seems to be with Am/pyx, as suggested by the general characters, the course of 

 the facial sutures, the simple glabella with pits, the cheeks with nervures, absence 

 of eyes, etc. 



Collections. — Mrs. Gray ; Museum of Practical Geology ; Hunterian Museum. 



Horizon and Localities. — Balclatchie Group (Llandeilo) : Balclatchie; Penwhapple 

 Glen. 



Genus TELEPHUS, Barrande. 

 I. Telephus fractus, Barrande, 1852. Plate IV, fig. 11. 



1852. Telephus fractus, Barrande, Syst. Silur. Boheme, vol. i, p. 890, pi. xviii, figs. 30—34. 

 ? 1854. Telephus ivegelini, A.ngelin, Pal. Scand., p. 91, pi. xli, tig. 23. 

 1884. Telefilms fractus, Tornquist, Undersokn. Siljaus. Trilobitf., p. 89. 



Specific Characters.— The description given by Barrande (op. tit.) may be 

 summarised as follows: Head very strongly swollen in a transverse direction. 



