THE LATER LARVAL DEVELOPMENT OF THE 



TRACHINIDAE 



(TRACHINUS VIPERA AND TRACHINUS DRACO) 



BY 



Dr. J. BOEKE 



With Plate IV. 



In a former paper ^) I described the eggs of the two species 

 of Trachinidae inhabiting the North Sea, viz. Trachinus draco and 

 Trachinus vipera. 



When describing the early development of these eggs I called 

 attention to the fact, that not only the eggs of the two species, 

 but also the young issuing larvae until the critical period of the 

 absorbation of the yolk-sac presented great differences both of 

 structure and of development of the larvae, which differences 

 were the more remarkable for the two species being so closely 

 allied. 



Trachinus draco. The eggs of the greater weever were provided 

 with a single oil-globule, developed rapidly and the embryo and 

 larva were characterised by their transpareucy and the almost 

 entire absence of pigment, viz. only a few patches of black pigment 

 (yellow by reflected light) occurring in characteristic distribution, 

 a dot on the snout, two conspicuous dark spots behind the eyes, 

 two smaller ones some way behind the auditory vesicles, a black 

 spot near the vent on the caudal side of the rectum, and a 

 pigmentbar half-way down the tail. A few pigmentcells are scat- 



1) On the early development of the weever fishes (Trachinus vipera and Trachinus 

 draco) Tijdschrift der Ned. Dierk. Vereeniging. (2) Dl. VIII afl. 2, 1903, pp. 148—158. 



