



1923.] Zoological Results of Expedition to Yunnan. 44] 
Caridina gregoriana appears to be distinguished from all 
other species of the genus by the large number of spinules on 
the dactyli of the third and fourth legs and by the peculiar 
modifications which these legs undergo in males. In general 
appearance the species is not unlike C. davidi Bouvier! from 
Southern Shensi and the environs of Pekin. Apart. however, 
from the two characters mentioned above C. davidi, which I 
have myself examined, is at once distinguished by the more 
depressed rostrum with fewer teeth on the carapace behind 
the orbit, the much shorter preorbital length of the anten- 
nular peduncle and the proportionately longer dactylus of the 
fifth leg. In Bouvier’s key to certain species, published in 
1913,* it comes nearest to C. propinqgua de Man, fromwhich 
it is readily separated by a large number of well-defined cha- 
racters, 
The remarkable modifications of the third and fourth legs 
of the male do not appear to have been noticed hitherto in 
to those seen in Paratya (=Xiphocaridina) compressa (de 
Haan) and P. curvirostris (Heller). A similar sexual differ- 
ence also occurs in Atyaephyra desmaresti (Millet), but in this 
genus the segment affected is not the propodus but the merus. 
Paratya and Atyaephyra are primitive genera of Atyidae and 
in this connection it is noteworthy that Caridina gregoriana, 
as shown by the comparatively great preorbital length of the 
antennular peduncle, is among the more primitive species of 
the genus to which it belongs. 
oth in the modified legs of the male and in the large num- 
ber of dactylar spinules on the third and fourth legs Caridina 
gregortana resembles the two species of Paratya referred to 
ese are striking features, but it would hardly be 
legitimate to assume without further evidence that the species 
orms a link between the two genera and was derived directly 
from Paratya by the suppression of the exopods of the legs 
and of the supra-orbital spines. 
Tribe BRACHYRHYNCHBHA. 
Family POTAMONIDAE. 
Potamon (Potamon) atkinsonianum (Wood-Mason). 
¥ j : 2 . Decap. 
ae T Grane Taface he Potamowatae, p38, Plate X,ig. 3. 
This species, which is common in the Himalayas from 
Darjiling to Simla and has once been recorded from tke Shan 


* See Kemp, Rec. Ind. Mus., xiii, p. = 
* See Remote; Rev. Biol. Nord. France, v, p. 126, figs. 1-3 (1893). 
