LARVAE OF DECAPOD CRUSTACEA 



PART V. NEPHROPSIDEA AND THALASSINIDEA 



By Robert Gurney, D.Sc. 

 (Text-figs. 1-39) 



INTRODUCTION 



IN the following paper I have dealt with larvae from the Discovery Collections, from the 

 Barrier Reef Expedition and from plankton collected by Prof. P. A. Buxton at Samoa, 

 and I am most grateful to the Discovery Committee, Mr F. S. Russell and Prof. 

 Buxton for the privilege of handling so rich a material. 



Included in it are larvae which can be definitely referred to the Upogebiidae and the 

 Laomediidae, but the majority belong to what I may call the Axiid-Callianassid group. 

 Detailed examination of the larvae of this group has shown such a baffling combination 

 of the characters supposed to be those of Axiidae and Callianassidae respectively that 

 it has proved impossible to draw any distinction between them. The examination of 

 this material has consumed much time, but the result has been so inconclusive that it 

 has seemed very doubtful if any useful purpose would be served by publishing de- 

 scriptions of these larvae. For the decision to do so I offer the following reasons. In 

 the first place it seems unlikely that it will be possible to add very much to our basic 

 knowledge of Thalassinid development since the adults are generally most difficult 

 to obtain, and also knowledge of the first stage alone, if it cannot be connected up with 

 later stages, will not carry us very far. Again, though obtaining the first post-larval 

 stage by moult from the larva will yield valuable information, it is not likely to be 

 conclusive, since the adult characters are so far from being attained at this stage. I 

 have a few post-larval specimens of Thalassinidea, but am unable to determine the 

 genus of any of them with certainty. 



I feel that the only means of approach to an understanding of Thalassinid larvae, and 

 therewith to contribute to knowledge of the relationship of the adults , is by trying to group 

 all the types of larvae that can be discovered according to such characters as seem to 

 have generic or family value, in the hope that a happy chance may place one group or 

 another in its proper systematic position. One thing seems practically certain — that 

 our present knowledge of the adults is quite inadequate to account for the types of 

 larvae known. The larva is easily captured, the adult may not be, and it is probable 

 that many more adult species remain to be discovered, and that some of them will 

 represent new genera or families. 



In attempting to identify larvae in preserved material the only clues to systematic 

 position are our knowledge of larvae of which the identity has already been established, 

 and those features of the adult which appear late in larval life. It is most unfortunate 



