ON THE ORKNEY" ANIMAL. 419 



Assures, that leave between them thin plates or la- 

 minae These laminae are formed by fibres that 

 radiate from the axis to the circumference of the 

 different cylinders f . The plates of the cylinders 

 are about the thickness of a shilling ; and the 

 spaces interposed between two plates, though not 

 always equal, are generally four or five times lar- 

 ger than that which is occupied by the thickness 

 of the cylindrical plate. The cylinders were nearer 

 to one another towards the centre and the cir- 

 cumferences, than in the space intervening J. 



In four places, two on the dorsal and two on 

 the sternal aspect, the fissures or sulci penetrate 

 through all the cylinders |j. These four deep sulci 

 serve for the attachment of two cartilaginous 

 tubes, that run longitudinally on the vertebral co- 

 lumn ; the one on the dorsal aspect, containing 

 the spinal marrow, and that on the sternal aspect, 

 the large blood vessels § . 



What occasions a singular appearance in these 

 vertebrae, is their want of processes. In the ver- 

 tebrae of many fishes, we observe nothing like ar- 

 ticular processes ; but in these vertebrae there are 

 neither transverse nor spinous processes, nor any 

 thing calculated to suggest an idea of them. These 

 vertebrae, therefore, are susceptible of inflection to 

 an equal extent dorsad, sternad, dextrad and sini- 

 strad. 



d d 2 



* Plate x. fig. 3, d, f Id. fig. 5. a, b> c% 



t fig. 4./. f| Id. fig, 6. b, c, d. 



f Id. fig, 3. B f c. 



