Tables for the determination of the plankton eggs of fishes 



occurring in the North Sea 



and neighbouring waters (excluding the Baltic) 



with 2 Plates 



i he measurements of the eggs are expressed in mm. Roman numbers indicate the 

 months; Arabic numbers after the months (e. g. VI: 1.15) indicate the average diameter 

 of the egg in the month mentioned. An * means that the information given for the 

 species so marlced requires to be confirmed and extended. 



A. Eggs containing oil-globules. 



I. Oil in the form of numerous globules. 



A. Oil-globules of a chrome-yellow colour, distributed at fairly equal distances over 

 the yolk and gradually becoming smaller during embryonic development. Pigment 

 yellow and black. Anus immediately behind the yolk-sac. 



Diameter of egg l .006 to l . 27 ( l .37 ?) ( VI : 1 . 1 5, VIII : 1 .099). Spawning-time V to IX. 

 Southern North Sea. Trachimis vifera Cuv. 



B. Oil-globules colourless. 



1 . United into several groups composed of verj? small globules ; pleuronectid anus. 



a. Few and small groups, each dissolving soon into one globule. 



Diameter of egg: 1.36 to I.38. Spawning-time V to VII. 



S. W. of Great Britain. " *Solea lascaris Bp. 



b. Several smaller and larger groups of oil-globules, which retain the same 

 appearance in the hatched larva. 



Diameter of egg: O.95 to 1.58 (IV: 1.36, V: 1.20, VI: l.ll). Spawning- 

 time III to VII (VIII?). 



Southern North Sea, Channel. Solea vulgaris Quensel. 



2. All the oil-globules of almost the same size and distributed at fairly equal 

 distances over the yolk. 



a. Yolk with marginal zone segmented (as is probably the case in all Solea 

 species). Pleuronectid anus. 



«. Oil-globules numerous (ca. 40) sometimes united into groups. 

 Egg large: 1.28 to 1.36. Spawning-time IV to VIII. 



S. W. of Great Britain. * Solea variegata Donov. 



