G. O. Sara. 



Fam. Sididæ. 



Gen. Latonopsis, G. O. Sars. 



Rem arks. — This genus was established by the pre- 

 sent author in 1888, to comprise an Australian species, 

 L. australis G. O. Sars. Though the genus is very nearly 

 allied to Latona of Müller, it has generally been admitted 

 by subsequent authors, and an apparently new species has 

 recently been added from North America as L. occidentals 

 Birge. There is, hovewer, another genus to which the pre- 

 sent one perhaps bears a still closer resemblance, viz, the 

 genus Pseudosida of Herrick ; but both Mr. Richard in his 

 Revision of the Cladocera, and Mr. Herrick himself in his 

 latest work, keep these 2 genera apart. The Brazilian 

 form, to be described below, though undoubtedly referable 

 to the genus Latonopsis, as denned by the present author, 

 in some points exhibits an evident approach to the genus 

 Pseudosida. Indeed, I do not regard it improbable, that in 

 future it will be found appropriate to combine all these 3 

 genera into one, in which case the oldest name, Latona, must 

 be retained. 



1. Latonopsis serricauda, n. sp. 



(Pi. I). 



Specific Characters. — Female. Carapace oblong, 

 not defined above from the head by any depression, height 

 somewhat exceeding the width, and about half the length, 



