NTOBE. • 143 



upper marginal furrow is all that is visible, and that is very strong and deep. The upper 

 surface is not well preserved ; but the caudal fascia on the under side is so broad as to 

 occupy the whole surface of the sides beneath, and the ornamental lines are rather close. 

 The same width of fascia is continued beneath the pleurae ; and the lines on it run directly 

 across them, as seen in our figure. The same sharp lines run round the under margin of 

 the head. 



Locality. — Llandeilo Flags. Penkerrig, near Builth, Radnorshire ; (Woodwardian 

 Museum). 



The passage from the Ogygides to the Bronfeida is rendered still more easy by a 

 MSS. genus, Bronteopsis, distinguished so far back as 1857, by my friend Prof. Wyville 

 Thomson, who was at that time carefully studying the Caradoc fossils of the Girvan district. 

 The genus is a very remarkable one, having all the characters of the Bronteidce, and will 

 be described under that family. But the crust appears to have been thin, not calcareous ; 

 and the habit of the tail is so much that of Barrandia, that it might well be mistaken 

 for an extreme member of the group we are describing. 



Again — Stygina leads from the Ogygides to the Illanides, besides having some affinities 

 with Bronteus. But we must first describe the typical Asaphi ; and therefore return on 

 our road to them by means of the genus Niobe (see diagram on p. 124). 



NioBE, Angelin, 1852. 



A genus instituted by Prof. Angelin to include a few flattened species of Asaphus, 

 which have the body flat, the axis broad, and the labrum pointed like that of Ogygia. 

 Asaphus frontalis, Dalman, is the typical species. The genus is strictly intermediate 

 between Ogygia and Asaphus. Range, Upper Cambrian to Lower Silurian. 



Broad-oval, depressed ; with a distinct broad axis, and a scarcely clavate glabella 

 which is slightly 4-lobed. Head-angles obtuse. Eyes approximate. The pleurae facetted 

 and grooved, not produced into points. Tail broadly margined, of a moderate number 

 of segments. Labrum with a narrow base and parallel sides ; the tip obtusely pointed 

 or slightly emarginate, not forked. Hypostome (in N. emarginula at least) without a 

 vertical suture. 



N. Icsviceps, placed by Angelin with this genus, should, I think, rather be referred to 

 Nileus among the subgenera of Asaphus. It has a perfectly smooth unribbed tail. 



Niobe Homfrayi, Salter. PI. XX, figs. 3—12. 



Niobe Homfrayi, Salter. App. Ramsay Geol. N. Wales ; Mem. Geol. Survey, vol. iii, 



p. 314, pi. vi, figs. 5—8, 1866. 



N. ovalis lata, 3 — 4 uncialis, depressa, axe subplano distincto, caudd semicirculari 

 semiradiatd. Glabella genis cequalis, urceolata. Oculi pra medio capitis positi. Labrum 

 acutum. Cauda sulcis lateralibus 4 — 5 abbreviatis, inter line atis. 



