EXPLANATION OF PLATE I-V. 



Plate I. Map of the Zuiderzee, scale 1 : 316.000. The depths are indicated in 

 feet at ordinary low tide. Red lines show the places where obser- 

 vations with „kuilnets" were made, the numbers added represent 

 the numbers of the list of observations. Blue lines and numbers 

 refer to observations on herring- and fiounder-fishing with the aid 

 of drift-nets. Numbers in black indicate the places where fishing 

 with bow-nets and standing nets was observed. 

 Plate II. Map of the Zuiderzee, on which the places where herring-spawn and 

 herring-larvae were observed are shown by red, and those where 

 smelt-larvae were met with by blue points. Numbers in red or 

 blue are again taken from the list of observations. 

 Plate III. Fig. 1. Larva of Gobius minutus, length 4 m.m. 29 diameters. 

 a. Part of the nutritive yolk. 

 Pig. 2. Larva of Osmerus eperlanus, length 5.2 m.m. 40 diameters. 

 This is the youngst larva of the smelt, I observed. Part 

 of the nutritive yolk is still to be distinguished (at d). 

 Fig. 3. Larva of Osmerus eperlanus, length 15 m.m. 7 diameters. 



At a the swimming-bladder may be seen, at è a first tracé 

 of the adipose fin. 

 Plate IV. Pig. 1. End of the tail of a larva of the herring of about 10 m.m. 

 88 diameters. 

 Fig. 2. End of the tail of a larva of the herring of 18 m.m. 58 dia- 

 meters. 

 Fig. 3. Herring-larva of Ty.) m.m. — youngest observed. 40 diameters. 

 Fig. 4. Herring-larva of 16 m.m. 61/2 diameters. 

 Fig. 4'. End of the tail of the larva of Fig. 4. 40 diameters. 

 Plate V. Fig. 5. Herring-larva of 32.5 m.m. 41/2 diameter. 



Fig. 5'. Young herring of about 37 m.m. Natural size. 



Fig. 6. Larva of Engraulis encrasicholus of 15 m.m. 6 '7.2 diameter. 



Fig. 7. Head of a larva of the herring of ± 23 m.m. 43 diameters. 



