6 G. 0. SAES. [NO. 9. 



and the less correct figures may thus in all probability be 

 accounted for by the small size of the species in connexion with 

 a less perfect condition of the microscope of the observer. 



A closer examination of this form evidently shows it not to 

 be a Chydorus, but a true Pleuroxus. In fact it is very nearly 

 related to the European species. P. aduncus of Jurine, having a 

 quite similar striation of the anterior part of the carapace. On 

 the other hand, it would seem to differ by a somewhat broader 

 and more rounded form of the carapace, by slightly shorter 

 antennulge. and by the infero-posterior corners of the carapace 

 being unarmed, whereas in the European species there are at 

 this place two small denticles. The form and armature of the 

 tail is very similar to that of P. aduncus, though the sinus of 

 the dorsal edge perhaps is a little slighter. The spirit specimens 

 had still conserved the dark corneous or chestnut colour mentioned 

 by Mr. King as distinguishing this form. The length of the speci- 

 mens does not exceed 0,56 mm. 



Several specimens of this form were found when closely examin- 

 ing the bottom residue of the tube by the aid of a strong hand- 

 magnifier. In most of the specimens the body was far extruded 

 from the carapace, apparently owing to the spirit having become 

 too diluted; but a few specimens were in a sufficiently good state 

 of preservation to allow the making of an exact drawing of 

 the animal. 



Chydorus Leonardi, King. 

 Chydorus Leonardi, King, 1. c. p. 258, PI. VII. C. ^ 

 This diminutive species, which only attains a length of Ofi 

 inn)., is very closely related to, if not identical wi 

 form of Chydorus occurring not rarely in the neighbourhood 

 Christtania, as also in Sweden. Prof. Lilljeborg has rec» j 

 separated this form from C. sphmricus (Mtiller) as a distffl» 

 species under the name of C. minor. I cannot at P resen * 

 any essential difference between the European and Australia 



