POST-LARVAL STAGES OF JASUS LALANDII. 123 



separated by an interval from a molar-like part. A trace of an endopodite 

 appears on the second maxilla, and the endopodite and endites of the proto- 

 podite appear on the second maxilla, The first maxillipede has the beginnings 

 of an exopodite and an epipodite. 



The pnerulus shows the typical characteristics of this stage — transparent 

 soft cuticle, few spines on carapace, bases of the third maxillipedes well 

 separated, antennular peduncle short, coupling-hooks on the appendix 

 interna. The puerulus in its natural state, though transparent, is not colour- 

 less and has the red spots characteristic of the phyllosoma. The condition of 

 the mandible indicates the method of transition between the phyllosoma and 

 adult state, the molar part becoming turned round, somewhat behind the 

 incisor part. 



Observation of the habits of the living animal shows that the naupliosoma 

 stage moves towards the light and undergoes ecdysis without descending 

 from the surface of the sea. The second stage at first also seeks the light, 

 but later on avoids it, and seems to descend from the upper layers of the 

 water on ecdysis. 



The exopodite on its first appearance has the same general appearance and 

 position with regard to the limbs as the rudiments of the gills. It is there- 

 fore suggested that the exopodite has arisen from a former gill. Observation 

 of the living naupliosoma seems to indicate that the exopodite has still an 

 important respiratory function. 



A feature common to all the stages of the phyllosoma examined is that the 

 last pair of well-developed walking-legs are relatively long and, probably in 

 all stao-es, act as steerino-oro-ans, as was observed to be the case in some 

 living specimens. The lengthening of this limb is chiefly in the first segment 

 of the endopodite, and this may prove to be a diagnostic characteristic of 

 the species. 



References and Bibliograpliy . 



(1) BouviER, E. L. — " Recherches sur le Developpement post-embryonaire 



de la Langouste commune [Palinurus vulgaris)." Journal of the 

 Marine Biological Association of the United Kingdom, vol. x. No. 2, 

 June 1914. 



(2) "Le Stade 'natant^ or 'puerulus' des Palinurides.'^ Trans- 

 actions of the Entomological Congress, 1912. 



(3) Claus, C. — Zeitschrift fllr wiss. Zool. vol. xiii. p. 428, 1863. 



(4) Gruvel, a. — " Contribution a Fetude generale, systematique et econo- 



mique des Palinurides." Ann. de I'Institut Oceanographique, 

 Tome iii. fasc. iv., 1911. 



(5) Milne Edwards, H.— Hist. Nat. Crust, vol. ii. p. 472, 1837. 



(6) StebbinGj T. R. R. — " General Catalogue of S. African Crustacea.'"' 



Ann. S. Afr. Museum, vol. vi. part iv. p. 376, 1910. 



