394 F. E. Cun-pcr Heed— The Genm Tnmidem. 



radial sulci ; towards the genal angles the rows diverge somewliat and 

 the pits are quite separate, and a short irregular row of a few pits is 

 inserted at the posterior outer angles of the cheeks. The lower plate 

 of the fringe of this species is not known. 



(2) Another imperfectly known species as regards its fringe is 

 T. Sedgiviclci, Salter,^ in which the upper surface of the fringe bears 

 two outer rows of large pits sunk in radial sulci, and several inner 

 rows of smaller pits "not strictly regular and more in number than 

 the outer rows' 

 T. subradiatus. 



(3) The rare species T. fhersiies, Salter,- only found by him at 

 Tramore, has a fringe with the upper surface possessing two regular 

 concentric rows of an equal number of pits of equal size radially 

 arranged, with an inner third row of fewer pits which are larger 

 and widely spaced in front of and at the sides of the glabella, and 

 are not liere radially ari'auged, but posteriorly are more closelv placed 

 and no larger than the outer rows and divide into two and finally 

 into three rows with their pits in radial lines near the genal angles 

 and tending to lie here in shallow grooves and in the same radii 

 as the outer I'ow of pits. The lower surface shows a well-marked 

 girder inside the two outer rows -which correspond in development 

 to those on the upper surface ; there is a similar inner third row 

 apparently continuous right round, and like the one on the upper 

 surface dividing into two and then three rows posteriorly. This species 

 has apparently never been figured. 



(4) T. radiatm, Murchison,^ was founded on some fragments of 

 head-shields showing a peculiar type of fringe described as follows : — 

 " Marginal pores arranged on the front of the liead in one or two 

 rows; on the sides in long radiating lines. Buckler square, lateral 

 spikes short." The examples of this species in the Jerinyn Street 

 Museum from Builth have in no case the complete fringe preserved, 

 and onlj' portions of the impression of the lower plate are present. 



(5) T. Ramsayi, Hicks.* It has recently been pointed out by me* 

 that this Trilobite is probably referable to the genus Dionide, and 

 must certainlj- be removed from Triniicleiis. 



EXPLANATION OF PLATE XIX. 



Fig. 1. Trinitcletis hibcrnicus, Eeed. Diagram of upper surface of fringe. 

 ,, la. Ditto. Ditto of lower surface. 



,, 2. T. fimbriatus, Murchison. Diagram of upper surface of fringe. 

 ,, 2a. Ditto. Ditto of lower surface. 



,, 3. T. Murcliisoni, Salter. Diagram of upper surface of fringe. 

 ,, 3a. Ditto. Ditto of lower surface. 



,, i. T. Nicholsoni, Eeed. Diagram of upper surface of fringe. 

 ,, 4a. Ditto. Ditto of lower surface. 

 ,, 5. T. seticornis (Hisinger). Diagram of upper surface of fringe 



(Sholeshook form). 

 ,, 5a. Ditto. Ditto of lower surface. 



^ Salter, Mem. Geol. Surv. , vol. iii, p. 516, pi. xii, fig. 9. 



" Salter, Dec. Geol. Surv., vol. vii, pi. vii, p. 7. 



^ Murchison, Silur. Syst., p. 660, pi. xxiii, figs. Sa, 36. 



■* Hicks, Quart. Journ. Geol. Soc, xxxi, p. 183, pi. x, figs. 1, 2, 1875. 



5 Geol. Mag., Dec. V, Vol. IX, p. 202, 1912. 



