490 PHYSIOLOGICAL SERI1>. 



root perforates each of the interdorsalia. A number of the 

 anterior spinal nerves converge as they pass outwards to 

 form the cervical and brachiul plexuses. The parts have 

 been finely injected. 0. C. 13-17. 



D. 751. A similar specimen of the anterior part of the spinal 

 cord of a Skate (Raid balls). The cord is surrounded by a 

 large subdural space. 0. 0. 1347 c. 



D. 752. A portion of the spinal cord of a Skate (Haia latin} ex- 

 p< >ed within the neural canal from above. Upon the left 

 side, the passage of the dorsal roots of the spinal nerves 

 through the interdorsalia is shown upon the section surface, 

 and in a similar way upon the right side that of the motor 

 (ventral) roots at a lower level through the dorsalia. The 

 dorsal and ventral roots emerge from, the cord in the same 

 transverse plane, but pass through the neural arches at 

 different levels, the ventral root perforating a dorsal him 

 and the dorsal root the succeeding interdorsalium. The 

 increasing obliquity of the nerve-roots, towards the lower 

 end of the specimen, in their passage to the walls of the 

 neural canal is very clearly shown. 0. C. 1347 D. 



TELEOSTEA. 



D. 753. The posterior end of the vertebral column of a Cod 

 (Gadus morrhua), showing from above the hinder portion 

 of the spinal cord. Before reaching the extremity of the 

 vertebral column it swells to form a large pear-shaped 



terminal ganglion, from the hinder end ol' which a delicate 

 terminal filament is given oft'. A >imilar enlargement i> 

 found in many bony fUh. 0. C. 1347 F. 



D. 754. The cranium and vertebral column of a Fishing Frog 

 (LopktHI pUctttoriuii), from which the dorsal parts have 

 been removed to expose the brain and >pinal cord in .%/'///. 



The anterior end of the cord, where it passo into the 

 medulla, is much enlarged and shows upon the dorsal 

 Hirface a pair of pyriform prominences, abruptly -\\ollen 

 in front and gradually decreasing to the normal level of the 



