POST-LARVAL STAGES OF JASUS LALANDII. 119 



as in the adult ; it has only a few setse. The exopodite (scaphognathite) is 

 well developed and provided with feathered setse. 



The first maxillipede (PI. 13. fig". 37) does not differ essentially from that of 

 the adult, but the endopodite is smaller and lies more to the inner side of the 

 exopodite. 



The second maxillipede (PI. 13. fig. 38) differs from the adult condition in 

 that the flagellum of the exopodite is not segmented, and the last segment of 

 the endopodite is provided with a short spine at its tip. 



The third maxillipede (PL 13. fig. 39) is characterised by a very short 

 exopodite, consisting of one undivided segment, about half the length of the 

 first segment of the endopodite, which lies alongside of it. The last three 

 segments of the endopodite are provided with long serrated spines on their 

 inner surface. 



The first pereiopod (PI. 13. fig. 40) shows the long basipodite of the 

 phyllosoma reduced to a mere ring of chitinous tissue, narrower on the upper 

 side than on the lower. At its narrowest point there is a projection of 

 irregular outline, and of a clear refractile substance ; this appears to be the 

 remains of the exopodite. 



Some of the spines of the limbs are of interest. In the phyllosoma there 

 occurs, at the distal end of the fourth segment of the leg, two spines evidently 

 of a defensive function. Here, as in the adult, their position is taken by the 

 projection, on which is the socket of the " ball-and-socket " joint, between 

 the segments, and their place is taken functionally by a single median spine 

 which now appears for the first time. It would appear that this pair of 

 defensive spines of the phyllosoma may be transformed to form the joint 

 of the adult, and this may be true also of all the other joints of a similar 

 nature. 



Fio-. 42. 



\y 



Epimera of oldest Phyllosoma, Puerulus, and adult. 



The pleopods (PI. 13. fig. 41) are all more or less similar, and have large 

 flat exopodites and endopodites, provided with feathered setse. There is 

 a coupling projection on the inner side of each endopodite, provided with a 

 feathered spine and hooks at its base. 



The telson has a second pair of spines, rather faintly marked, situated 

 behind the pair already seen in the last phyllosoma. 



9* 



