680 NOTE ON THE YOUNG OF THE SAW-FISH SHARK, 



Fig. 4. —Early stage in the development of the larva before the appearance 

 of the larval appendages, a, outer larval membrane ; b, inner larval 

 membrane ; e, blastoderm with indications of segments ; d, yolk ; 

 e, rudiment of dorsal organ. 



Fig. 5. — Later stage. a, outer membrane; b, inner membrane; c, yolk: 

 d, dorsal organ ; e, larval appendage : /, eye ; g, and h, antennae ; 

 i, pereiopoda ; k, pleopoda ; I, telson. 



NOTE ON THE YOUNG OF THE SAW-FISH SHARK 



(PRISTIOPHORUS CIRRATUS). 



By William A. Haswell, MA., B Sc. 



About 18 months ago female specimens of Pristiophorus with 

 young, were obtained with the trawl off Port Jackson. The young 

 were fully formed, l-esembling the parent in everything except 

 size, so that this peculiar genus of Sharks, like many others is 

 viviparous. More recently I obtained from specimens received by 

 the Australian Museum from the Fisheries Commissioners a series 

 of foetuses which exhibited a very much earlier stage of the develop- 

 ment, the yolk-sac being still very large and the external gills being- 

 still conspicuous. In this stage the foetuses (1) which were from 

 seven to nine in number in each female, are particularly interesting 

 from their possessing a rudimentary shell, which, though for the 

 most part extremely delicate, presents at one point a spiral rudi- 

 ment proving unmistakably its true nature. In one case this 

 rudimentary shell was found detached and lying free in the cavity 

 of the uterus. In the advanced stage first examined it had entirely 

 disappeared. A similar rudimentary shell lias been shewn to exist in 

 several other viviparous genera. Mustelus, Sphyrna&nd others (1), but 

 nothing has hitherto been known of the development of this peculiar 

 Australian genus. On comparing the weights of the early stage 

 plus the yolk sac, with the later stage, I found, as was to be 

 expected from their relative size, that the latter was considerably 



[I) £ee Balfour's Embryology, Vol. II. 



