60 GUIDE TO THE FOSSIL REPTILES, AMPHIBIANS, FISHES. 
Order II.— CYCLIJE. 
Table-case The problematical small skeleton named Palceospondylus 
E. gunni (Fig. 55), from the Middle Old Eed Sandstone of 
Caithness, seems to represent an otherwise unknown Order, 
which may perhaps be referred to the Agnatha. It is never 
more than about two inches in length, and the collection in 
Table-case E is thus supplemented by some enlarged wax- 
models of the fossil ingeniously made by the donor, Prof. 
Fig. 55.—Restoration of Palceosjpondylus gunni , from the Middle Old 
Red Sandstone of Caithness; nearly twice nat. size. (After R. *H. 
Traqnair. Table-case E.j 
W. J. Sollas. The head exhibits tentacle-shaped processes 
round an opening at the front end, and the roof of the brain- 
case is not sufficiently hardened for preservation. Bars 
which seem to be gill-arches occur below the back of the 
head, and they are connected in some way with a pair of 
plates extending behind the head. There are ring-vertebrae, 
and the tail is heterocercal, with hardened rays. There is no 
skin-armour. 
Palceospondylus shows some striking resemblances to the 
lampreys, and it is quite possible that the existing Marsi- 
pobranchii are the degenerate survivors of the Agnatha. 
CONODONTS. 
Table-case Minute tooth-like bodies named Conodonts (Fig..56) found 
E. detached in Palaeozoic rocks from the Lower Silurian to the 
Fig. 56.— Cambrian Conodonts, ten times nat. size. (After G. J. Hinde. 
Table-case E.) 
