312 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [<Apr. 19, 
as I have ascertained by the examination of the greater number of 
specimens of this species yet found, m the general outline of the cara- 
pace, which was longer in proportion to its breadth than in the print, 
and not defined by such regular curves. The real proportions are 
much more correctly given in the figure of the Homothorax (Old Red, 
tab. 31. fig. 6) ; for the Homothoraz is, I find, the under side of the 
Pamphractus, drawn from a rather imperfect specimen of Pterichthys 
hydrophilus, which did not indicate the divisions of the plates. In 
the museum of our Highland Agricultural Society here [Edinburgh], 
there is a specimen of yellow sandstone from Dura-den, Fifeshire 
(Upper Old Red), which exhibits several individuals of this species. 
All of them present their ventral surface, and in all the central part is 
more or less mutilated, so that the small lozenge-shaped plate cannot 
be traced ; but the transverse and longitudinal sutures which sepa- 
rated the four large plates are distinctly visible. One of the most 
striking specific distinctions of the creature consists in the length and 
bulk of the arms, and the comparatively great prominence of those 
angular projections by which they are studded on the edges,—pro- 
jections which seem to be but exaggerations of those confluent lines 
of tubercles by which the arms of all the other species are fringed. 
“Tt may seem idle work to be writing and thinking so much about 
one little fish that perished myriads of ages ago; but the heaven-im-. 
planted instincts of man’s nature are greatly wiser than man himself, 
and it is in due accordance with these that we should be thus engaged. 
I have a little curious boy of five years, who intently takes note of 
all I do, and instinctively imitates me; and in him I recognize the 
instinct as eminently wholesome, because essential to his development 
asman. And are we not also children, in an early stage of mental 
growth, and engaged, like the boy, in intently examining the handiwork 
of our Father? The records of His wisdom, inscribed in the rocks, 
are often, as in this instance, obscurely written ; but that very ob- 
scurity serves only to whet curiosity the more, and, by concentrating 
upon them the powers of the attention, brings into greater prommence 
the profound meanings which they convey.” 
Description of Species. 
PrericHTHys Latus. Mon. Old Red, Tab. 3. figs. 3 & 4. 
The figures of this species show the abdominal plates ; but, as they 
are both casts of the interior, the central plate appears larger and 
more rounded than it would be if seen from without. The tubercles 
of the plates in this species are coarse, and frequently confluent. 
PTERICHTHYS TESTUDINARIUS. ‘Tab. 4. figs. 1 & 2. 
I have stated in the foregoing remarks that I am inclined to believe 
that fig. 1 is the ventral, fig. 2 the dorsal view of this species. 
PTERICHTHYS PRODUCTUS. Tab. 3. 
Fig. 1 shows the ventral surface. The left-hand portion of the 
drawing does not belong to the Pterichthys, but shows a crushed 
