Summary1Several pueruli of Jaszcs laltmiiii have been kept alive to succeeding or post‐puerulus stage, which shows the following changes:‐a. The red spots on the underside of the body disappear, and the whole and the wholeb. The spines of tlie carapace (of a definite number in tho puerulus)become much more nutiierous.c. The antennules lose the antennular screen of the pnerulus.d. The mandibles reseriible those of the puerulus in having three teeth, but differently disposed, and n cutting‐edge has appcared. Denticles appear between and on the first two teeth, as well as along the cutting edge. The palp has become three‐segmented.e. The exopodites of the pereiopods have disappeared.f. The exopoclites of the third maxillipedes are longer, by the addition of a flagellum.g. The cervical groove is well marked at the sides of the body.h. The pleopods have become sinaller, especiirlly the endopodite, which is now devoid of seta; the coupling hooks and seta of the uppemlix iiiterna hnve disappeared.h. The telson has additional spines.2The post‐puerulus diflers from succeeding stages in the following respects:‐a. Cuticle uncalcified.b. The incisor part of the mandible is provided with dcnticles on the margin of its thick cuticle.c. The pleopods show no sexual differentiation.D. The third inaxillipedes are separated a t their bases.The occurrence of it naupliosoma stage has been confirmed in the New Zealand Jusus Ialanilii, and the phyllosoina and puerulus