148 



MARINE BIOLOGICAL LABORATORY. 



PANTOPOD-LAR VA 



hydroids. The first pair are three-jointed, — counting 

 the movable claw of the chelae, — the second and third 

 appendages on each side are two-jointed. These last 



two appendages represent the 

 palps and ovigerous legs of 

 the adult. The body ends 

 anteriorly in a rounded pro- 

 boscis. The digestive tract, 

 beginning at the mouth at the 

 distal end of the proboscis, 

 passes through the proboscis 

 as a tube triangular in cross- 

 section and opens out into 

 the wide stomach within the 

 ^3 body proper. There is no 



posterior opening to the digestive tract, but from the 

 stomach runs forward into the mandibles a pair of 

 diverticulae. The larva has a brain lying dorsal to 

 the oesophagus, which is connected by two commis- 

 sures with a pair of ganglia ventral to the digestive 

 tract. There are in all two pairs of these ventral gan- 

 glia, the pairs more or less fused together ; and behind 

 these, and completely detached from them, is a thicken- 

 ins: of ectoderm which indicates the commencement at 

 this place of a third pair. The larva has no heart nor 

 reproductive organs at this stage. 



It is needless to follow here the changes which this 

 Pantopod-larva (Dohrn) undergoes as it is metamorphosed 

 into the adult. The body elongates, new appendages 

 appear seriatim, the proctodaeum invaginates and puts 

 the digestive tract posteriorly into communication with 

 the outside world, and the second or third pairs of 



