236 W. M. Tattersali. : Two new My sides. [Vol. II, 



(2) Antennal scale. — The second joint of the antennal scale 



of P. pengoi is described as small, and only about one 

 ninth of the whole antennal scale in length. In 

 P. assimilis the second joint of the scale is rather 

 large and equal to between one fifth and one quarter 

 of the length of the scale. 



(3) Czerniavsky describes in P. pengoi two secondary spines 



at the terminal part of the tarsus of the thoracic limbs 

 in addition to the dactylus, giving the whole limb a 

 tri-unguiculate appearance. No such secondary dac- 

 tyli appear to be present in P. assimilis though, as 

 shown in fig. 6, there are sundry setae in the position 

 shown by Czerniavsky for the secondary nails. It may 

 be that Czerniavsky has mistaken the setae for spines 

 and this apparent difference between his species and 

 the present one may not actually occur. 



Otherwise the two species are in very close agreement and the 

 occurrence in brackish water in India of a species of this obscure 

 genus is of special interest. 



Genus MacropsIvS, G. O. Sars. 



Macropsis orientalis, sp. nov. 



(Plate xxii, figs, i — 9.) 



The differences between M. orientalis and the only other 

 known species of this curious genus, M . slabberi, are mainly differ- 

 ences in the proportions which the various parts bear to one 

 another. 



These dift'erences are most conveniently brought out in a 

 table of comparative measurements of the two species, side by 

 side. It will be best, therefore, to give such a table first and then 

 to discuss the characters of the two species, one by one, in the 

 light of the table. 



The measurements of M. slabberi are taken from specimens 

 from Saltash Bridge, near Plymouth, which I received through the 

 courtesy of the Marine Biological Station at Plymouth. 



The sum of the differences between the two species is that 

 M. orientalis is a much more robust form, M. slabberi, on the other 

 hand, being very slender and attenuated, with the various append- 

 ages correspondingly elongated. 



