The intra-marsupial development of Niphargus schellenbergi is divided into three phases: within the chorion, embryonic intermoult and juvenile intermoult. The disappearance of the chorion divides the first phase from the second. A double exuviation exists between the last two. The chronology of the embryonic development and of the beginning of post-embryonic development is established. On hatching the juvenile N. schellenbergi has one pair of hepatopancreatic caeca. During the first post-embryonic intermoults the ventral hepatopancreatic caeca, posterior caeca and anterior caecum are formed. The relation between posterior caeca and the aorta is described. The study of calcium storage before moulting showed that calcareous concretions located in posterior caeca and midgut have the typical form, volume, quantity and distribution of the species. This calcium accumulation process occurs in the midgut following the first posternbryonic exuviation. It is only when the sixth exuviation is attained that storage in the posterior caeca is similar to the one in adults. The urate containing cells located at the lower face of the pericardial septum begin to accumulate urate spherules 15 days before hatching. They vary in form, volume, localization and composition, and so may be considered as storage sites for urate, pigments and various ions (P, K, Ca, S, Cl, Na, Mg) which are returned to circulation.