958 EMMERICH ON THE MORPHOLOGY, CLASSIFICATION 
which may probably have induced Steininger to ascribe simple 
eyes to the Calymene concinna from the Eifel, but no one has 
yet entirely denied their former power of vision: such a badly 
advised scepticism has only been asserted with respect to the 
Trilobites of the clay-slate and grauwacke. What I have said 
of Calymene Blumenbachii holds good with respect to the other 
Trilobites which were considered as blind, belonging to the 
genera Paradowides, Brongn., and Ellipsocephalus ; they both 
have a hole which penetrates the upper covering of the cephalic 
shield at the locality where the eyes were situated, the latter 
themselves have disappeared. Now whether it is more probable 
that the eyes have in this case decayed, or been annihilated, 
and thus left the hole owing to the easy destructibility of the 
horny membrane, or that the hole was originally there, is a 
question which, in my opinion, is placed beyond doubt by com- 
parative anatomy. 
Now if most of the Trilobites which were formerly considered 
blind have been proved to have been furnished with eyes like 
the rest, there still remains a small number in which we have 
hitherto not been able to trace the existence of eyes. These 
are the Trilobites designated Ampyx by Dalman, and arranged 
by him under the genus Asaphus, and the Trilobites of the genus 
Cryptolithus, Green, Trinucleus, Murchison. In neither of them 
have we yet been able to detect anything like eyes. I have had but 
poor materials, I regret to say, for my own researches on Ampyz ; 
the only specimen in the Berlin Museum exhibited no traces of 
eyes nor of the facial suture, the casts in plaster of Paris equally 
as little, and the decriptions of Dalman, Sars and Portlock like- 
wise do not make any mention of either one or the other. This 
absence of the facial suture leaves us in complete uncertainty as 
to whether we have really to deal with perfect cephalic shields, 
or whether the maxillary shield may not have separated itself 
from the forehead portion in a similar manner, as this is gene- 
rally found to be the case with Paradoxides gibbosus from the 
slate of Andrarum ; the eyelid-like appendage is also wanting in 
the latter, so that the lateral margin of the forehead portion ap- 
pears to be rectilinear, and therefore like a perfect cephalic 
shield. It is very desirable that geologists and palzontologists, 
who have occasion to collect species of Ampyzx in their places of - 
deposit, should endeavour to ascertain whether maxillary parts, 
which have got separated, and belong to the apparently perfect 
