BEITISH FOSSILS. 



11 



tumidis cum margine genarum covjluentihus ; lohis lateralihus tumidis, supremo sub- 

 triangulato antice obliquo, reliquis fere rotundis hrevissimis ; genis declivibus tuberculatis 

 viarginatis, angulis rotundatis ; oculis elevatis brevibus curvatis ; pygidio semicircular i 

 tumido ; axi lato convexo 8-9-annulato, apice obtuso nec marginem attingente ; lateribus 

 convexis, costis 7-8, radiantibus simplicibus, margine angusto. 



The peculiar character of this species, which a good deal resembles P. sclerops 

 Dalman, consists in the absence of any separating furrow between the upper lobe 

 of the glabella and the outer margin of the cheek, the glabella thus seems to be 

 drawn out into it on either side. 



Localities. — Capel Garmon, Llanrwst ; near Penmachno ; Pont-y-Glyn Diffwys ; and 

 Bala ; all in the Bala or Llandeilo rocks of North Wales. 



6. Phacops Jukesii, — n. sp. [P. sclerops, var., Dalman, Pal., t. 2. fig. 1 g. (mala) ?] 



P. capite unciam etplus lato, fere quam longo ter latiore, convexo {granuloso ?) ; glabella haud 

 elevatd antice valde dilatata, postice contractd, utrinque tri-lobd; lobo basali transverso lineari, 

 secundo paullo majore rotundato, supremo magno triangulato, frontali maxirao transverso 

 toto oculo elevato brevi curvato imminente, lobo cervicali elevato nec lato ; genis latis 

 marginatis, [angulis rotundatis ?] ; sulco verticali forte exarato ; lined faciali impressd ; sulcis 

 axalibus profundis. 



This curious species, which we have only just now detected in the collections from 

 Bala, differs materially from the next, in the comparatively equal size of the lateral 

 glabella lobes. The upper one is large and triangular, but not nearly so large as in 

 P. conopkthalmus, and the second is distinctly rounded and larger than the basal 

 lobe, instead of being contracted and almost lost, as in that species. 

 Locality. — Bala limestone, west of GeUi grin, Bala. [Survey Coll.] 



7. P. conopkthalmus, Boeck. sp. \_Calym. sclerops, var. Dalman, Pal, t 2. fig. 1 d?'] Tril. 

 conzcopA. Boeck Gcea Norveg. (1838), 1.4. Phacops con., Emmrich Dissert. 21. Asaphus 

 Powisii (head only), Murch. Sil. Syst, t. 23. f. 9. Calym. Odini (Eichw.), De Vern. Geol. 

 Euss,, t. 27. f. 8. P. sclerops, Burm., ed. 2. (1846), t. 4. f. 5. excl. syn. (icon bona, ab 

 editione prima multo emendata.) F. conophthalmus, ib. p. 91. Chasmops Odini, M'Coy, 

 l.c. 1. 1 G. f 22, 23. P. conophthalmus, Angelin, Pal. Suec. (1852) t. 7. f. 5, 6. 



P. ovatus, magnus; capite valde transverso, fere quam longo ter latiore, granuloso, convexo; 

 glabella convexd, antice valde dilatata, postice angustatd, utrinque bilobd, lobo mediano omnino 

 contracto obsoleto, basali transverso lineari, supremo maximo triangulato, supra paullum 

 sinuato ; frontali rhombo-trigonali maximo nec oculo imminente ; lobo cervicali lato ; genis 

 convexis late marginatis ; angulis in cornua lata extensis [interius rotundatis^ oculo brevi 

 valde curvato ; lined faciali impressd ; cauda (associata J lata punctata, vix marginata, 

 axi conico, lateribus angustiore, 9-10 annulato ; costis lateralibus 8 arcuatis, omnibus 

 duplicatis. 



This remarkable species is abundant in the Silurian strata on the Baltic coasts ; it is 

 equally common in Britain, but although fragments are abundant, we have only 

 seen perfect specimens of the head in the Woodwardian Museum. I collected these 

 in company with Professor Sedgwick, and with them was associated the tail above 

 described, which could hardly belong to any other species. It is found with 

 fragments of the head in some other localities, and agrees well also with that figured 

 by Professor Burmeister. But the figure given by Angelin represents the tail 

 as considerably more pointed, and we have specimens from Wales more of this 

 character ; there are other species of Phacops in which similar variations occur. 

 The heads figured in the " Silurian System," from the Caradoc sandstone, belong 

 to this species. Angelin has figured two other Phacops with very similar lobes to 

 the glabella, but it is possible his P. bucculenta and P. macroura may prove but 

 varieties of this. 



