158 SILURIAN TRILOBITES. 



lobe. The axis runs about two thirds down the tail, is narrow, not half the width of the 

 side-lobes, of about eight distinct ribs and a terminal portion, all strongly covered by 

 arched striae, the tip quite prominent {a in fig. 1). The sides are radiated by eight 

 equal strong furrows, which run direct to about two thirds to the flat margin, but are 

 sinuated in their course. The five hinder ones scarcely reach half way. The whole tail 

 (as shown in the splendid specimen, fig. 1, in the collection of Mr. Blunt, of Shrewsbury, 

 who has had it for twenty years) is covered with a strong oblique striation. And the 

 incurved fascia beneath is the widest and most coarsely ribbed that I know in any British 

 species. It resembles that of the Bohemian fossils quoted above. Asajjhus nohilis, Barr., 

 however, has a larger cephalic shield and longer in proportion, and the tail has a longer 

 and slenderer axis, more strongly ornamented. The side-furrows, which in ours are 

 crowded at their origin, and so appear radiated, are in the Bohemian fossil more parallel. 



There is an Asaphus (referred to Ptychopyge) described by M. Lawrow in the 

 'Verhandl. der Russ. Kais. Min. Gesellschaft/ 1858; pi. xiii, fig 2, which has radiating 

 ribs (but fewer) and a similar sculpture. 



Localities. — Caradoc only; Rhiwlas, near Bala (figs. 2, 3, Woodw. Mus.), Berwyn 

 Mountains (Mr. Blunt's collection, fig. 1). Co. Louth, Ireland (figs. 4, 5, Mus. Pract. 

 Geology). 



ASAPHUS (B.) LATICOSTATUS. PI. XVIII, fig. 6. 



IsoTELUS (Basilicus) LATICOSTATUS, M'Coy. Synopsis Woodw. Museum, pi. i e, 



fig. 18 a, 1851 (not of Green's Monogr. p. 45, 

 which is a Phacops). 



AsAPHUS LATICOSTATUS, Salter. Morris's Catal., 2nd ed., 1854, p. 100(Builth locality 



only). 



Asaph. [B.) planus, 5 uncias longus ? Cauda lente convexa, semiovata, obtusa, nargine 

 angusto striato, hand concavo. Axis angustus longiconicus § cauda longus, sulcis axalibus 

 exaratis bene notatus, quartamque partem latitudinis efficiens, annulis rectis 10 planatis, 

 per medium interruptis ; apice haud abrupto. Limbus lente convexus, costis 10 plants 

 marginem fere attingeniibus, sulcisque profundis, ad apices recurvatis. Fascia angustis- 

 sima. 



We only know the tail of this remarkable species, which Prof. M'Coy has unac- 

 countably referred to the Asaplius laticostatus of Green. The American cast (No. 13 of 

 the Monograph) shows that species to be a large Dalmania, which we have lately found in 

 Britain.^ Prof. Green himself rightly compared his species with the Phacops {Dalm.) 



^ In Mr. H. W. Edgell's cabinet. The specimen seems to be from Upper Llandovery rocks. Green's 

 specimen has no locality, but he quotes it from the Helderberg (Ludlow) series. 



