Plate XVII. 



Fig. 1. Larva of Tliickback newly liatclied, April 24, 1889; magnified 35 times. 

 Pigment as seen by reflected liglit. yh. yolk. 



Fig. 2. Larva of same two days after hatching, April 23, 1889. Same magnification 

 pt. pectoral fin. ht. heart. 



Fig. 3. Larva of Flounder [Pleuronectes flems), two days after hatching, February 20, 

 1889, from egg artificially fertihsed ; magnified 35 times. 



Fig. 4. Larva of same six days after hatching, February 24, 1889, from the same 

 lot as the preceding ; same magnification. 



Fig. 5. Young Flounder taken in Mevagissey Harbour, April 2, 1889 ; drawn April 5 ; 

 magnified about 18 times. 



