56 



OLD RED SANDSTONE ETSHES. 



the margin or rim of tlie shield are very densely set conical or pyramidal tubercles of 

 the size of a pin's head and larger. The apices of some of these tubercles are curved so as 

 to form little hooks, The upper surface of the shield, to judge from a piece seen at the 

 lower portion of the figure, which may, however, belong to another plate, was ornamented 

 with equally close-set tubercles, so closely set and of such irregular angular form that 

 their impress in the matrix has the appearance of a network. But what is chiefly 

 remarkable is the presence of a set of grooves, independent of the tubercles, winding 

 about amongst them in such a way as to mark out irregular areas of a quarter of an inch 

 or less across, giving an appearance wdiich is seen on some Reptilian scutes, and which is 

 but feebly rendered in Mr. Dinkel's drawing in PI. XIII. 



General Bemarh. — This species was pointed out to me some time ago by my 

 friend Mr. Lightbody, who has a few fragments besides the rim here figiu'ed. I have 

 great pleasure in naming this very interesting form after one who has done so much in 

 the investigation of these matters, and has given me so much assistance in my task. 



It is impossible to say what subgenus this Cephalaspis would fit into, or whether it 

 would require a new one. Its large size and very definite peculiar ornamentation render 

 it probable that we shall soon hear of it again. Extending inwards from the rim are seen 

 in the specimen the 'lateral floors' of the shield. The tubercles on their surface are 

 much smaller than those on the rim itself. 



Genus 2. — Auchenaspis, E(/erton. Quart. Journ. Geol. Soc, vol. xiii, 

 p. 28G, 1857. 



Derivation. — av^jn-, the neck ; aawiq, a shield. 



Characters. — Scutum in duas partes divisum, anteriorem semicircularem in qua sunt 

 oculi positi, cornil)us lateralibus magnis instructam majorem, posteriorem oblongam 

 minorem. 



a. Auchenaspis. — Cornibus lateralibus modestis. 



/3. EuKERASPis.^ — Cornibus lateralibus longissimis, cellulis marginalibus magnis. 

 1. Auchenaspis Salteri, Efjerton. PL XIII, figs. 7, 8. 



Auchenaspis Salteki, Egerton. Quart. Journ. Geol. Soc, vol. xiii, pi. ix, 1857. 

 NaMe. — After the late Mr. J. W. Salter, of the Geological Survey. 



' el, intensitive ; Kepas, cornu ; do-Trt's, shield. 



