4 Papers from the Department of Marine Biology. 
collected and prepared skate embryos of the species Rava punctata at 
the Zoological Station at Naples. 
I wish to express my appreciation and thanks for the facilities for 
research offered me by the Harpswell Laboratory, Maine, during the 
summer of 1915; by the United States Bureau of Fisheries, Woods 
Hole, Massachusetts, during the summer of 1916; and by the Marine 
Biological Laboratory, Woods Hole, Massachusetts, during the summer 
of 1916 and May 1917. I am greatly indebted to Professor E. G. 
Conklin for criticism and advice throughout this work. Most of all 
do I wish to acknowledge my thanks to Professor Ulric Dahlgren, 
whose help and guidance have made this work possible. 
DISTRIBUTION. 
A study of the spinal cord of the skate was first made in order to 
determine the exact anterior-posterior distribution of these large cells 
of unknown function. It had been noticed by Dahlgren that the cells 
TEXT-FIGURE 1.—Diagram of the skate to 
show the region of the tail in which the large 
cells of the spinal cord are found. The anterior 
limit of the cells is indicated by the line drawn 
through the tail at the level of the sixty-fourth 
vertebra. The anterior limit of the electric 
organs is indicated by the line drawn through 
the root of the tail at the level of the thirty-third 
vertebra. The shaded regions represent the 
parts of the spinal cord examined in the skate in 
which the calculation of the total number of 
these large cells was made. 
pec. f. pectoral fin. ver. 1. first vertebra. 
pel. f. pelvic fin. ver. 33.  thirty-third vertebra. 
reg. A. region A. ver. 88.  eighty-eighth vertebra. 
t. f. 1. first tail-fin ver. 120 + one hundred and twen- 
t. i 2. second tail-fin. tieth vertebra, ap- 
proximately. 
TABLE 1. 
No. of 
Region. At level of— cells 
per mm. 
A......| 64to 70 vertebre. 0.324 
Bae 74 to 78 2.302 
Chaece 84 to 87 2.250 
1D whan 90 to 92 4.755 
1D Rereaet 105 to 107 3.470 
Basasca) LI2to lds 3.380 
ver.120+ 
were always found in regions of the spinal cord that were opposite to the 
electric organs, none appearing in that part anterior to the electric 
organs. 
