LARVAE OF DECAPOD CRUSTACEA 



419 



The growth factor remains about 1-3 or less, and one cannot therefore assume a greater 

 rate of growth for earher stages. If that is so we are forced to conclude that there are as 

 many as thirteen stages, and that Gilchrist's larva of 3-8 mm. is stage 4. Bouvier and 

 Santucci agree in finding nine stages in Palinurus vulgaris, and Stephensen found the 

 same number in Scyllarm arctus. Gilchrist's larva is even less developed than stage II 

 of Palimirus, and it is difficult to believe that it can represent a later stage. In any case 



Fig. 26. PamiUnis D, 8 mm. St. 407. 



there seems to be a gap of three unknown stages between this larva of 3-8 mm. and the 

 youngest of the Discovery specimens. 



Our knowledge of the development of the European forms is not so securely founded 

 that we are entitled to assume a similar course in other genera and species, and having 

 regard to the wide distribution and great size reached by some of them, there may well be 

 a longer period of larval life and a greater number of stages. Consequently I have, for 

 the purposes of this report, accepted a provisional arrangement into thirteen stages, 



6-2 



