4 



BEITISH FOSSILS. 



Scattered granules, like those on the head, are sparingly distri-^ 

 buted over the more convex parts of the body rings, and occur 

 both on the axis and sides of the tail (fig. 2*). The spines are all 

 smooth. 



Variations.- — We have only three specimens, and between our 

 figs. 1 and 2, and fig. 3, the only differences seem to arise from the 

 greater pressure to which the latter has been subjected. In fig. 3> 

 preserved in soft black slate, the axis is widened and depressed, the 

 pleurae less convex, and their spines more divergent, and the glabella 

 is somewhat widened and deeply furrowed. In addition, the cheek 

 margin appears to overhang more, and to be contracted much more 

 decidedly above the spine. The terminal spines of the tail, too, are 

 rather more crowded. 



Affinities, — Except with the species next described, and with 

 which I formerly united it, there is no British fossil which has any 

 near resemblance. Among foreign species, A. mira, Barrande, has a 

 pair of neck spines, but has the eyes far backwards, and is a true 

 Acidaspis ; A, Prevosti and A. Dufrenoyiy Barrande, which belong, 

 perhaps, to the same section with A. Jamesii, have but four terminal 

 and two extremely long primary spines to the tail ; and A. Ver- 

 neuilii and A. vesiculosa, which belong to the section Trapelocera, 

 and possess each two neck spines, have the eyes remote, as in the 

 Wenlock species quoted in our next description. 



Locality and Geological Position. — Llandeilo Flags. Fig. 1, 2^ 

 from the sandy schists of Newtown, Waterford. Fig. 8 is in black 

 slate, Duncannon, Wexford. (Mus. Geol. Survey, collected by 

 Capt. James, B.E.) 



ACIDASPIS BISPINOSUS. 



Decade VII. Plate VI. Fig. 4. 



Diagnosis. A. capite convexissimo, glahelld loho mediano ovali gibbo per 

 totum capitis extenso, lobis lateralibus utrinque tribus minutis linearibus ; 

 oculis ante medium genarum positis ; cervice bispinoso. 



Synonyms. A. bispinosus, M'Coy (1846), Synopsis Sil. Foss. Ireland, 

 pL4. fig.7. (not Odontopleura bispinosa, Emmrich, 1845), see M'Coy, Lc. 



The head only of this species is known, and it is remarkable 

 for the extreme gibbosity of the central lobe. Our specimens are 

 about four lines wide ; the one figured by Professor M'Coy is double 

 that size. 



Head scarcely thrice as wide as long, and the convexity equal to 

 three fourths the length. The glabella extends nearly the whole 



