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CEPHAiASPIDiE. 
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Cephalaspis murchisoni, Egerton. 
[Plate IX. fig. 6; Plate X. figs. 1-4.] 
( aor. < 
1857. Cephalaspis murchisonii, Sir P. Egerton, Quart, Journ. Geol. Soc. 
vol. xiii. p. 284, pi. ix. fig. 1. 
1857. Cephalaspis ornatus, Sir P. Egerton, ibid. p. 285, pi. ix. figs. 2, 3. 
[Imperfect shield ; British Museum.] 
1870. Hemicyclaspis murchisoni , E. R. Lankester, Fishes Old Red 
Sandst. pt. i. (Pal. Soc.), p. 51, pi. viii. fig. 6, ph ix. fig. 1, ph xii. 
figs. 3, 4. 
Type. Shield ; un knowm 
The type species of the suhgenns Hemicyclaspis , of moderate size. 
Shield sharply rounded in front; orbits placed nearly midway 
between the anterior and posterior margins ; cornua rudimentary. 
Superficial ornamentation consisting of widely spaced, regularly 
arranged, large tubercles, with intervening small tubercles. Scaly 
trunk about three times as long as the shield. 
Form. Sf Loc. Ludlow Tilestones and Lower Old Red Sandstone 
Passage Beds : Herefordshire. 
The specimens presented by George H. Piper, Esq., recorded below 
and shown in the accompanying Plates, make known the exoskeleton 
of this species almost completely, and add important items to our 
knowledge of the morphology ot the Cephalaspidians in general. A 
restoration is attempted in the woodcut (fig. 24), and the following 
are detailed notes on the collection. 
Fig. 24. 
Cephalaspis murchisoni , Egert.— Side view, restored from specimens discovere 
by George H. Piper, Esq. [jNos. P. 6023, &c.] 
The precise form and proportions of the anterior shield have 
already been determined by Lankester (fig. 25), and the fossils under 
discussion are quite similar to those previously studied. The absence 
of posteriorly prolonged cornua is distinctly shown ; there is the 
well-defined high “ posterior ridge ’’behind the “ postorbital valley,” 
and the usual three layers entering into the constitution of the shiel 
are readily distinguishable. There is also no trace of sensory 
canals. 
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