42 G- 0. Sårs. 



North America, by Mr. Richard from Celebes, and by Mr. 

 Weltner from East Africa. Its geographical distribution is 

 accordingly very extensive. 



15. Ilyocryptus sordidus, (Lie vin). 



(PL VII, figs. 11—13). 



Acanthocercus sordidus, Lièvin, Die Branchiopoden der Danziger 

 Gegend. Neueste Schriften der naturf. Gesellsch. in Danzig, 

 p. 34, Pl. Vin, figs. 7—12. 



Remarks. — In one of my aquaria a form of Ilyo- 

 cryptus developed, which at once showed itself different from 

 the preceding species by the rudimentary condition of the 

 setæ of the antennæ, and the consequent entire absence of 

 swimming power. On a closer examination this form proved 

 to be identical with the well-known European species, I. sor- 

 didus of Lièvin. To show the identity more clearly, I have 

 given on the accompanying plate a figure of an adult female 

 specimen together with 2 detail-figures, the one represent- 

 ing one of the antennulæ together with the labrum, the other 

 the caudal part. The specimens were of a bright red colour, 

 and did not exceed a length of 0.46 mm., whereas the length 

 of fully grown specimens of the preceding species was about 

 1 mm. 



Occurrence. — The aquarium in which this form 

 appeared, was prepared with mud from Ipiranga. 



Distribution. — Besides from Europe and Brazil, 

 this form has been recorded by Prof. Birge from North 

 America; and I have myself raised it both from Australian 

 and Chinese mud. This species, accordingly, also has a very 

 wide geographical distribution. 



