Dr. H. Riley on the Squalor aia. 87 



On casting the eye along the upper surface of the column of the fossil, it is 

 easy to recognise traces of the spinal canal in the form of a very superficial 

 groove; which is more evident in the posterior than in the anterior half. 



Prom the above details we should be inclined (o consider this animal as 

 having a column resembling that of the Squales. 



The thoracic and pelvic members are next to be considered. 



They are greatly injured, hardly an entire piece remaining, and it is evident that with the view 

 of rendering the form of these parts more clear and decided, great liberties have been taken with 

 the specimen. 



The scapulae have disappeared, but we can make out the remains of pieces 

 corresponding to a sternum and pelvis. 



We can likewise recognise the radiated form of the thoracic and pelvic 

 members, and can easily trace the anterior member backwards as far as the 

 pelvis, circumscribing an oval space, with the vertebral column running- 

 through its centre. 



This space would correspond to the seat of the alimentary canal and organs 

 of generation. 



It is dotted with an immense number of small spines, of the same form with 

 those so often alluded to, but seems to have suffered from the measures 

 resorted to for an advantageous display of the vertebral column. 



Those parts, which in the fossil put on the appearance of radii, belonging 

 to the thoracic member, are distinct from each other, but do not present any 

 traces of joints, a character in which they differ greatly from the Rays, whose 

 radii are jointed. The spaces between these radii have been apparently cut 

 into grooves by a knife, which has injured them. 



The forms and arrangement of the pelvic radii are by no means dissimilar 

 from those of the Rays. There are no signs of the powerful claspers to be 

 found in the males of this family. 



We are not able, for want of a greater number of skeletons, to determine 

 the original form of the transverse piece in the region of the scapulae. The 

 portion which must have passed over the vertebrae, corresponding to the 

 scapulae, has been destroyed, whilst the part which is to be seen lying under 

 them remains, but has been greatly mutilated. 



This portion in the Rays would correspond to that transverse cartilage, 

 which connects the thoracic members with each other under the bodies of 

 the vertebrae. By its position and flattened form, increasing in width at 

 each extremity, it resembles the piece occupying the same position in the 

 Rays, and would correspond to the sternum. 



