58 



OLD RED SANDSTONE EISHES. 



3. EuKERASPis pusTULiFERUs, Agcissiz. PI. XIII, figs. 9 — 14. 



ScHLERODUs PUSTULIFERUS, Sil. Svst., pi. iv, figs. 27, &c. ; Siluria, pi. XXXV, 



figs. 9—12. 



Plectrodus mirabilis, Agass. Sil. Syst., pi. iv, figs. 14, &c. ; Siluria, pi. xxxv, figs. 

 3—8. 



Name. — PusfiiJiferi/s, bearing pustules, on account of its fine tubercular ornament. 



Stratigrapldcal Position. — The Downton Sandstone of Ludford Lane, near Ludlow. 



Characters. — Posterior portion of the shield not known ; cornua twice as long as the 

 central or vertical diameter of the anterior portion of which they are processes ; a series of 

 six cavities (cellulse marginales), woodcut, fig. 31, c. m., on either side excavated in the 



Fig. 31. 



Fig. 32. 



Ornament of the same, magnified 

 7 diameters. 



Diagram outline of head-shield of EuJceraspis pmtuliferus. 

 a. o.p. orbital prominence ; c. nt. marginal cavities ; p. o. v. post- 

 orbital valley ; o. p. interorbital prominence. 



substance of the shield; a similar pair of cavities (appearing like orbits in fig. 13, 

 PI. XIII) are placed posteriorly to the true orbits and on either side of a very marked 

 prominence {i. o.p. in the woodcut), like the interorbital prominence of Ceplalaspis (seen 

 in PI. XIII, fig. 10). The true orbits are deeply sunk, and are seen in figs. 13 and 14 ; 

 the right orbit, which is preserved in the specimen drawn in fig. 13, and lies anteriorly 

 to and somewhat to the left of the right hand of the two oblong cavities, there drawn, is 

 not clearly seen. The antorbital prominences {a. o. p. in the woodcut) are very marked 

 and prominent in this form; as to the antorbital fossa3 I am uncertain. The whole 

 surface is covered by a very fine densely set series of circular tubercles of very small size 

 and great regularity, extending on to every prominence and furrow of the shield. The 



