MARINE BIOLOGICAL STATION AT PORT ERIN. 23 



No. 3. Plaice Larva hatched 3 minutes, 6"5 mm. in 

 length, x 15. 



" In No. 3 the light was moved slightly to one side, so 

 that the illumination was partly by transmitted and 

 partly by reflected light, and the light being no longer 

 directed into the lens, a dark background was obtained. 

 This method is very useful in photographing delicate 

 structures. 



" Nos. -± to 9 (PL III) show the changes by which the 

 bi-laterally symmetrical larva becomes an asymmetrical 

 flat fish. All are enlarged about 7 times. 

 No. 4. Larva just hatched, length 6'5 mm. 

 No. 5. Larva hatched 7 days, length 7*5 mm. 

 No. 6. Larva of length 9*5 mm. 

 No. 7. Larva of length 10 mm. 



' This specimen shows a greater relative growth dorso- 

 ventrally than longitudinally, a sign of commencing 

 metamorphosis which is supposed to occur about the 30th 

 day after hatching. 

 No. 8. Larva of length 11*5 mm. 



" This shows the rotation of the cranium through its 

 longitudinal axis, and the consequent carrying over of the 

 left eye. 

 No. 9. Larva of length 13 mm. 



' This shows the metamorphosis progressing, and the 

 next stage examined showed it completed. 



' The first five photographs were from ova or larvae in 

 the batching boxes; the last four specimens were obtained 

 From the spawning pond- ;il the Biological Station. All 

 the specimens were photographed while alive, excepl 



\<>. 9. In this case I wailed until the heart stopped 



beating, in order to show thai structure satisfactorily. 



" As to the apparatus used : — A deal board, lour Eeel 

 long and - ; \ inches wide, carried on one side two rails. 



