Manchester Memoirs, Vol. Ix. (191 6), No. %. 7 



arises a special process with which the clavicle articulates. 2 

 Our observations have served to convince us of the 

 great general accuracy of Dr. Traquair's restoration but 

 one well preserved fish gives evidence of the occurrence 

 of a large scale covered lobe in the second dorsal, and a 

 similar but a smaller lobe in the anal fin. The external 

 structure of these fins is in fact quite similar to that of the 

 typically " Crossopterygian " pelvic limb. 



Glyptolepis paucidens, Ag. 



The Manchester material does not permit us to add 

 anything to our knowledge of the skull structure of this 

 type, but a small slab collected by one of us at the famous 

 quarry of Achanarras shows numbers of well preserved 

 scales of Glyptolepis paucidens associated with the some- 

 what imperfect impression of the caudal part of the verte- 

 bral column. This specimen is scarcely in a condition to 

 afford detailed information but shows quite conclusively 

 that the vertebral column of Glyptolepis is of a temno- 

 spondylous nature. At the anterior end the elements are 

 naturally arranged and seen to show neural arches 

 attached to pleurocentra which extend about half the 

 height of the column, the condition being apparently 

 rhachitomous. Posteriorly the neural arches with their 

 attached pleurocentra have been dragged away from the 

 series of hypocentra so as to suggest that the condition is 

 nearly embolomerous. In both regions the ossifications 

 appear to be paired and are slender segments of rings. 

 Despite its imperfection this specimen is of considerable 



- Throughout this paper the terms for the clavicular apparatus are those 

 ordinarily employed by students of fish and are not to be interpreted as 

 implying the acceptance of any view of their homology with those of 

 Tetrapods. 



