igi7.] S. Kemp : Notes on Crustacea Decapoda. 205 



last four abdominal somites at 

 most very bluntly carinate dor- 

 sally ... ... ... sty lifer us, 



b. No subapical dorsal tooth on ros- Milne-Edwards, 

 trum ; carpus of second peraeopods 

 as long as merus or fingers ; last 

 abdominal somite nearly two thirds 

 as long as carapace ... ... japonicus, 



2. Palm of second peraeopods little if at all Ortmann.' 

 swollen, carpus at most only a trifle 

 shorter than chela [at most 5 teeth on 

 lower border of rostrum]. 



a. One or two small subapical dorsal 



, teeth on rostrum ... ... mniii, Sollaud.' 



b. No subapical dorsal teeth on ros- 

 trum ,.. ... ... 77J0dfStuS, HcWcY. 



B. Carapace without branchiostegal spine ; carpus 

 of second peraeopods at least one and a half 

 times as long as chela. 



1 . Rostrum shorter, with 3 to 5 inferior teeth ; 

 last three peraeopods shorter, fifth pair 

 extending beyond antennal scale by little 



more than length of dactylus ... fliiiuiiiicola, 



2. Rostrum longer, with 6 to 10 inferior sp. nov. 

 teeth ; last three peraeopods longer, fifth 



pair extending beyond antennal scale 

 by dactylus and at least one half of 

 propodus ... ... ... potamisciis, 



sp. no\\ 



These species form^ I believe, a natural group, though some 

 of them possess very unusual characters. Leander tenuipes, to- 

 gether with a related but imperfectly known W. African species, des- 

 cribed by Aurivillius as L. hastatus, exhibits in the excessive length 

 and slenderness of the last three thoracic legs a feature paralleled 

 among Macrura only in the deep-sea Neinatocarcinidae.^ A link 

 between these species and more normal types is, however, afforded 

 by L. annandalei, a most interesting form obtained by Dr. Annan- 

 dale near Shanghai.. 



The two last species mentioned in the key differ, so far as I 

 am aware, from all described representatives of the genus in the 

 complete absence of the branchiostegal spine. This character 

 might, indeed, be held to possess generic value ; but the spine in 

 question is not infrequently very small in other species of Leander 

 and the affinities of the forms in which it is absent appear to be 

 unmistakably with the more normally constituted L. mani and L. 

 modestus. 



Of the seven species that I have myself examined, L. styliferus 

 and L. tenuipes are apparently seasonal immigrants to brackish 

 water, ascending estuaries and tidal rivers, possibly for breeding 

 purposes, when the monsoon floods are abating. The two species 



^ I have not seen specimens of this species. 



* In the Nematocarcinidae, however, the extreme length of the legs is due 

 to the lengthening of the merus, ischium and carpus, whereas in Leander tenuipes 

 and its ally the merus and ischium are nearly normal in length and the carpus 

 quite short, the propodus and daetylus being the segments that are attenuated. 



