SC't. DtCr,. S^pt. Dor.L. 



*^L>* 



-^?^ii^. m 



l.Orh MrJ.Pt.a 



Through the courtesy of Prof. S. W. Ranson the artist of the Medical School, 

 Mrs. Frain, finished in ink the author's outline sketches for figures 1 to 4, 9, 10, 

 15, 23, 26, 32, 37, 39, 44, 47, 48, 50 to 54, 64, 65, 70, 72 and 74. 



Fig. 1 Lateral view of young Mustelus canis a few days after escape from the 

 .uterus to show the distribution of the sensory canals and the pit organs. The 

 pores of the canals and the pit organs are drawn to a larger scale than the out- 

 line of the specimen, otherwise they could scarcely be seen in a specimen of this 

 size. X \. 



Fig. 2 Dorsal view of the head of a larger specimen (garter). X f. 



Fig. 3 Ventral view of the same head. Note the short line of pit organs on 

 either side of the scar of the 3'olk stalk. X f . 



11 



