PLATE 1 



EXPLAXATION OF FIGURES 



1 Graphic reconstruction of the caudal spinal nerves of a 20 cm. Polistotrema 

 (Bdellostoma) series as seen from the left side, but which in reality should be 

 from the right side but for an error in making the reconstruction. It shows the 

 complete distribution of the motor and sensory components of the spinal nerves 

 in the tail region and the relationship of the motor and sensory components to 

 each other in each nerve. It portrays also the irregularities of the last three 

 nerves, the innervation of the M. cordis caudalis, the presence of isolated or 

 clustered peripheral nerve cells along the course of some of the sensory and mixed 

 nerves and the existence of seven or eight muscle spindles in the ventro-cephalic 

 end of the M. cordis caudalis. X 14. 



ABBREVIATIONS 



C.A., caudal artery 



C.H., caudal heart 



C.V., caudal vein 



D.Myo., dorsal border of myotomes 



D.R., dorsal root (radix posterior) 



D.S., dorsal spine 



L.M.B., large muscle bundles in the 



M. cordis caudalis 

 M.C.C., M. cordis caudalis 

 M.D.B., median dorsal cartilaginous 



bar 

 M.S., muscle spindle 

 M.T.C., M. transversus caudalis 

 Muc.S., mucous or slime sac 

 Nc, notochord 

 N.C., nerve cell 



R.Cut.M., ramus cutaneus medius 

 R.Cut.S., ramus cutaneus superior 



R.D.M., ramus dorsalis or posterior 



(motor) 

 R.D.S., ramus dorsalis or posterior 



(sensory) 

 R.M.C.C., motor rami for M. cordis 



caudalis 

 R.V.M., ramus ventralis or anterior 



(motor) 

 R.V.S., ramus ventralis or anterior 



(sensory) 

 Sp.Cd., spinal cord 

 Sp.G., spinal ganglion 

 V.Myo., ventral border of myotomes 

 V.R. (1), cephalic ventral or anterior 



root 

 V.R. {2), caudal ventral or anterior 



root 

 V.T., ventral veno-lymphatic trunk 



196 



