POST-PUERULUS STAGE OF JASUS LALAKDII. 199 



(8) Colour. 



The colour of the post-puerulus stage has been described above. This, as 

 pointed oat. appears in the later pueruhis stages, and is accompanied hj the 

 appearance of the new spines of the succeeding stage. To be quite accurate 

 therefore, if we are to regard the increase of spines as a characteristic of the 

 second stage, we must also consider the coloration to be so, the puerulus 

 being strictly colourless, except for the bright spots on the under surface, 

 found also in the phyllosoma. 



Neither in the puerulus nor post-puerulus does the median rostral tooth 

 meet the antennular segment as in the adult, a fact already noted in some 

 specimens in the British Museum, from Stewart island, New Zealand, and 

 briefly described by Caiman (3), who was the first to throw light on the real 

 significance of the genus Puerulus. In a specimen with well calcified cuticle 

 and 32 mm. in length it just touches it. In a larger specimen of about 

 40 mm. two slight projections of this segment were seen on each side of the 

 tooth, but not clasping it, as in the adult. 



The same is true of the relative length of the antennular and antennary 

 peduncle, the former being markedly the shorter both in puerulus and post- 

 puerulu?, and even in much more advanced specimens, about 55 mm. in 

 length, they are only about equal, though decidedly longer in the adult. 

 This feature therefore cannot be regarded as characteristic of the puerulus only. 



A comparison of the earlier stages, the naupliosoma and phyllosoma, of 

 the Jasus lalandii of the Cape with that of New Zealand is of interest. 

 That this first stage is also found in the New Zealand crawfish is now 

 established. In the vear 190G Mr. G. M. Thomson (8) described a staee of 

 Jasus lalandii which resembles the naupliosoma (4), but the antennules, not 

 the antennae, are described as bearing plumose setse. A further discrepancy 

 is the presence of five pairs of pereiopods, instead of three found in the Cape 

 phyllosoma. Mr. Thomson kindly sent me a copy of his note, which is 

 readity overlooked as it is included in a paper by Mr. Anderton on " Obser- 

 vations on New Zealand Fishes." I suggested a re-examination of the 

 New Zealand larva, in view of what I had found in that of the Cape crawfish, 

 and in the year 1916 Archey (1), without however any previous knowledoe 

 of Thomson's paper, redescribed and figured these early stages of the New 

 Zealand crustacean, and concluded that the first larval form is identical 

 with that which I described in 1913. There are, however, some slight dis- 

 crepancies: thus, for instance, he figures free setse on the endopodites of the 

 first and second pereiopods. This may be accounted for by the fact that 

 the cuticle of the naupliosoma is first shed in these parts, and some of the 

 subcuticular setae may have thus become free, this part of the limb representing, 

 therefore, part of the phyllosoma limb. 



