ON SOME ARMOURED FISHES. 
5 
“ Ludlow-bone-bed ” — originally described by Agassiz — have 
now been referred, by M‘Coy, Salter, and myself, to the class 
Crustacea, there are a sufficient number of true ichthyic frag- 
mentary-remains left, justly to entitle this bed to retain its 
primitive name. 
Many of the early discoveries of fish-remains, however, have 
to be cancelled. For example, “ the defensive spine of Onchus ,” 
announced in 1847 as detected in the Bala limestone by the 
geologists of the Grovernment Survey ; and in the same year, 
from the upper part of the Llandeilo Flags, by Professor Sedg- 
wick, are only the tail-spines of a large species of “ Pod-shrimp,” 
Ceratiocarisi a bivalved phyllopodous crustacean, nearly related 
to the living Nebalia, but immensely larger in size. The same 
explanation must be applied to Professor Phillips’s 66 Onchus 
spines ” from the Wenlock shale, and Sedgwick’s fish-remains 
from the Wenlock limestone; whilst the Sphagoduspristodontus 
of Agassiz proves to be only a part of the foot-jaw of Pterygotus. 
As a set-off against these fossil crustaceans having been 
spuriously elevated to the rank of - fishes, it is not without 
interest to find that for 17 years the discovery of fish-remains 
of the genera Scaphaspis and Cephalaspis in Cornwall and 
South Devon was precluded from recognition by the decision of 
Professor M‘Coy, who determined them to be sponges! belong- 
ing to the genus Steganodictyum .* 
A similar incorrect diagnosis led Professors Bomer and 
Kner to refer the Cephalaspidean head-shields, from the Lower 
Devonian of the Eifel and of Russian Grallicia, to the genus 
Archceoteuthis among the fossil cuttle-fishes. They are now 
placed by Lankester in the genus Scaphaspis ; Sc. dunensis of 
the Eifel being quite closely related to Sc. cornubicus , from 
Mudstone Bay, South Devon ; whilst Scaphaspis Kneri is un- 
distinguishable from Scaphaspis Lloydii , from Herefordshire 
(Lankester). 
A revision of the Cephalaspidean Fishes at the present time, 
presents us with 15 genera and about 53 species, some three of 
which are, however, doubtful. 
To Mr. John Edward Lee, F.Gr.S., of Torquay, belongs the 
honour of the discovery (in 1859) of the earliest known head- 
shield of a fish in the Lower Ludlow beds of Church Hill, 
Leintwardine, Shropshire. This, the oldest known vertebrate 
* Mr. Pengelly- states that be has upwards of 300 fragments of Pterasjrides 
from the Devonian rocks of Mudstone Bay, South Devon, which have lain 
in his cabinet for years, having been formerly supposed to he sponges. Yet, 
before 1848, Mr. Peach, the veteran geologist, had announce I the discovery 
of fish-remains in Cornwall, in the u Trans. Roy. Geol. Sue. of Cornwall,” 
being the identical fossils which, in 1851, Prof. McCoy called Steganodictyum , 
and referred to the Amorphozoa. 
