44 
also the pleura of the thorax and tail, thus giving the animal the 
appearance of great beauty, and probably serving also for defence. 
The body, too, is sometimes tuberculated, especially the head, 
thus adding to the beauty of the creature. 
Respecting the under aspect of the creature, Mr. Turner said but 
little was known. It was true, that a few years ago, we heard of some- 
body having found, in Canada, what he believed to be the legs of a 
Trilobite, but Mr. Turner was not aware that the discovery had been 
confirmed. Hundredsof these creatures had passed through his hands, 
but he had never seen anything like legs or swimmers; though he 
believed he had found something like antenne in one or two species. 
Whether these creatures had legs, whether in the absence of legs 
they crawled along on the bottom of the sea in which they lived, 
whether they propelled themselves through the water by means of 
the tail, as the lobster propelled itself, he did not know. But some 
at all events—the Calymene, for instance—had the power of rolling 
themselves into a kind of ball, like the wood-louse, in which state 
they were buried. The only appendages of which we are at 
all certain are the eyes and the lips. The eyes are extremely 
interesting. In some genera—for example the Encrinurus—the 
eyes were stalked, as in the lobster; in others they were sessile ; 
while some trilobites are considered to have been blind. Further, 
the eyes of many are beautifully and numerously faceted, as in the 
Phacops and others ; some are large, and many so small as scarcely 
to be visible to the naked eye; and it is singular that these small 
eyes have always been found detached from the animal that bore 
them. What a wonderful series of thoughts is suggested to the 
mind as one gazes upon these beautifully preserved relics of a time 
so long passed away. The fossil remains -of trilobites are more 
generally found in fragments than whole ; occasionally separate 
segments only are met with. The reason for this is, that the 
attachment between the several divisions—head, thorax, and tail 
—was weaker than that between the segments of the same division, 
and that decomposition and the separation of these parts occurred 
before burial. Just the same was the case with the vertebrata, the 
mammalia, the saurians, and the fishes, and with the bivalve mollusea, 
whose shells are often found apart. 
Now there is as wide a departure from the trilobite among the 
ancient crustacea as from the lobster type among the modern crustacea. 
Trilobites vary very much, both in size and form ; some have been found, 
both in Wales and America, nearly two feet long, while others are so 
small as to be scarcely visible to the naked eye. The variations in the 
form of the head, in the number of rings in the thorax, or tail, the 
presence or absence of spines, the form of the eyes, and the like, 
give rise to the division of the trilobites, but it is thought that some 
