256 Records of the Indian Museum. [VOL Ve 
(The length of the sixth abdominal 
segment of the adult male sel- 
dom falls short of its minimum 
breadth; the seventh segment is 
hardly ever broadly triangular .. GECARCINUCINa (Old 
World, except Europe). 
I + The length of the sixth abdominal 
| segment of the adult male is 
usually much less than its mini- 
} num breadth; theseventhsegment 
is usually broadly triangular : 
male appendages peculiarly heavy 
[emantdsblunt:. Se a .. PSEUDOTELPHUSINAS 
(New World). 
( Merus of external maxillipeds elon- 
| gate: dactyli of crawling-legs non- 
| spinose au a8 .. TRICHODACTYLINA 
2 4 (New World, chiefly 
S. America). 
Merus of external maxillipeds not 
elongate: dactyli of crawling-legs 
strongly spinose a Fem. 
(Efferent branchial channels _pro- 
| duced to the edge of the front .. DEcKENtINa (E. Africa, 
Seychelles). 
| Efferent branchial channels not ab- 
normally produced - .. POTAMONINA 
(Old World). 
Subfamily POTAMONIN4. 
In this subfamily the terminal joint of the mandibular palp 
is never deeply cleft into two lobes, though it may sometimes be 
thickened and plumose at base. The abdomen of the adult male 
is almost never abruptly contracted distally; its sixth segment is 
almost always much broader than long, and its seventh segment is 
almost always broadly triangular. 
It is safe to say that the subfamily is restricted to the Old 
World, being represented in Europe, Africa, Asia (abundantly), 
the Malay Archipelago, and (doubtfully) in Australia. One species 
—-Potamon (Geotelphusa) chilense, Heller—is said to have come 
from Chili; but both the generic determination and the locality 
require confirmation, for there is nothing either in the description 
or in the figure published that affords conclusive evidence of its 
position. 
The diagnostic features and the broad geographical dis- 
tribution of the constituent genera are shown in the following 
synopsis :— 
