12 



BRITISH FOSSILS. 



binis solum dlstincto, laterihus plants, lobis anticis curvatis et distinctis, reliquis ad basin 

 connatis, apicibus ovatis. 



Locality. — Bala limestone ; Bala, frequent ; Hendre wen, Cerrig-y-druidion, Denbigh- 

 shire. 



Section Actinopeltis. Corda. 



Glabella inflated, the upper lobes indistinct. 



6. Ch. clavifrons. Balm. sp. ? \_Calymene, Dalman, Palsead. 59. not of Hisinger. Loven 

 Ofv. Kongl. Vetensk. Akad. (1844), 63, 64 ?] Sphcerexochus juvenis, Salter (June 1848), 

 Mem. G. Surv. vol. ii. pt. 1. pi. 7. fig. 1-3 (exclude 3 6). -S*. clavifrons, ib. Errata, p. viii. 

 Cheirurus clavifrons, in Appendix, Pal. Foss. Wood-w. Mus., t. I F. fig. 11, and 1 G. fig. 9. 

 Ceraurus, M'Coy, ib. 154 (1851.) 



C. capita sesquiunciali semi-elliptico, in juveni rotundiore, convexissimo ; glabella maxima 

 ovali gibbd, genis latiore, granulosa ; sulcis duobus anticis brevibus obscuris, basali profunda 

 fere ad cervicalem decurvato lobumque subovatum ambiente; genis declivibus scrobiculatis 

 brevi-spinosis ; cauda axi longo, 4-annulato, articulo ultimo rotundo, lateribus utrinque 

 trispinosis, spinis valde incequalibus vix basi connatis, primo ad basin lato, brevisidcato, 

 secundum longe superante, hdc integro angusto tertium. brevem scepe obsoletum multo excedente; 

 spinis omnibus retrorsis subparallelis. 



The glabella, when perfect, shows small regular granules or tubercles widely scattered 

 all over it. The punctations too on the cheeks are rather small, and scattered. 

 The terminal spines of the tail in some specimens are very short and obtuse, and 

 the whole tail is in some shorter and broader than in others, even from the 

 same locality, and the spines consequently more divergent at their bases. 

 There are some points of difference between our fossil and that which Loven has 

 carefully described from Dalman's original specimen and we may have again to 

 recur to the name juvenis as above quoted. The Swedish species is described as 

 having long straight head spines, the glabella nearly as wide as the cheeks. 

 Ours, now that we have more perfect specimens of the head and caudal shield 

 from Ireland, shows short head spines, and the inflated glabella is certainly wider 

 than the cheeks. In all other respects Loven's description applies well. By the 

 description also of the tail of the C. ornatus, Dalm., given by the same author with 

 the above, it would appear that this species had a caudal shield precisely similar to 

 that of ours. 



Localities. — Llandeilo and Bala rocks ; in South Wales, Sholes Hook, Haverfordwest. 

 In North Wales, Bala, abundant ; Cader Dinmael, Denbighshire ; near Llanfyllin, 

 Montgomeryshire — in Upper Bala beds ; in Westmoreland, Applethwaite Common ; 

 in Ireland, Chair of Kildare, — frequent, and of large size. 



August, 1853. 



J. W. Salter. 



