Yol. 56.] SPECIES OE TALMANIA. 617 



pleura bears to the outer the ratio of 5 to 4. The inner part is 

 straight and flat, while the outer curves downward and backward. 



The second and fifth segments bear two small tubercles near the 

 centre of the axis, while the first, sixth, and seventh bear large 

 tubercles on the axis near the junction with the pleurae. 



Some of the pleurae bear two small tubercles on the anterior side 

 of the groove, near the centre of that part lying between the fulcrum 

 and the axis. The pleurae of the sixth and fifth segments, on the 

 other hand, bear only one large tubercle on the posterior side of the 

 groove — the former close to the axis, and the latter midway between 

 the fulcrum and axis. 



Prom the examination of all the specimens at my disposal, I 

 infer that the ornamentation (as might be expected) is not a 

 constant feature. 



The pygidium is almost an isosceles right-angled triangle, the 

 right-angle being produced into a long caudal spine equal in length 

 to, or slightly longer than, the axis of the pygidium. The margin 

 is entire, and formed of a smooth and more or less flattened border. 

 The axis bears traces of thirteen segments. 



Horizon and Locality. — All the specimens come from the 

 Wenlock Shales, and were collected by the late Dr. Grindrod during 

 the excavations made through the shale for the Malvern Tunnel. 

 These specimens formed part of the Grindrod Collection. 



Affinities.- — This species bears a strong resemblance to, and is 

 undoubtedly allied to, certain varieties of Phacops {Dalmania) 

 caudatus, especially those more nearly approaching Ph.lonyicaudatus. 

 But the differences are so well-marked as to preclude the possibility 

 of its being the young of that species. First the spines round 

 the head have, so far as I know, never been observed in any other 

 species of Dalmania, or at any rate in the species of the caudatus- 

 group. Again, the height of the head-shield and the distance 

 between the eyes are both larger in proportion, being in the ratio 

 of 13 to 11. The surface-ornamentation is apparently of a more 

 severe type than one would expect in a young specimen ; also the 

 presence of a caudal spine of such dimensions seems to be a distinctive 

 character. 



Its nearest ally appears to be Phacops {Dalmania) ne.vilis, Salter's 

 Ph. (pdontocheile) caudatus, var. y. 



Phacops {Dalmania) nobilis, sp. nov. (PI. XXXIV, figs. 1-3.) 



This species seems to have attained a considerable size. Its total 

 length is about 2| to 3 inches in what is apparently an adult form. 



The head-shield is semicircular in outline, and moderately con- 

 vex: the whole surface being tubercular, with a tendency to become 

 spinose. The tubercles are not round, but elongated parallel to the 

 axis. As regards the lobes of the glabella, the frontal is almost 

 circular in outline. Behind it occur the axillary lobes, three in number. 

 The glabellar furrows do not pass across the glabella, but are 

 interrupted in the middle of their course by a well-marked ridge. 



