PISHES OF THE GULF OF MAINE 



489 



the egg proper and its covering membrane, and it about doubles the total diameter. 

 The plaice eggs we have taken in the Gulf of Maine have averaged about 2.5 mm. 

 in diameter, but they have been reported as small as 1.38 and as large as 3.2 mm. 

 in other seas, depending-on the breadth of the perivitelline space. 



Incubation occupies 11 to 14 days at a temperature of 39°, and it seems that 

 the eggs gain in weight as development proceeds, for in the Gulf of St. Lawrence 

 Huntsman found the newly spawned eggs floating on the surface, but those which 



Fia. 244.— Locality records for plaice eggs (#) and larvae (iO 



were nearly ready to hatch hanging suspended at a depth of some 10 fathoms. We 

 have no first-hand information to offer on this point. During the development 

 of the egg minute black and yellow pigment ceUs are scattered over the embryo, 

 not aggregated into any diagnostic clusters, but very soon after hatching (which 

 takes place when the larvae are 4 to 6 mm. long) the pigment gathers in five definite 

 groups — one on the gastric region, one about the vent, and three post anal bands, 

 a pattern simUar to that of the larval witch flounder (p. 515). 



