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PACIFIC SCIENCE, Vol. IX, April, 1955 
Barnard (1940) considered Talitropsis a syn- 
onym of Talitroides , which should be ranked 
either as a separate genus, Talitroides , or as a 
subgenus, Talitrus {Talitroides) . He states, "I 
suggest therefore that the maxilliped palp and 
the 2nd joint of peraeopod 3 be regarded as 
the diagnostic features of Talitrus (s.s.) and 
that, following Schellenberg, all the other 
species be grouped together either generically 
or subgenerically.” Schellenberg (1942), 
Stephensen (1943) and Reid (1947) accept 
Talitrus and Talitroides as separate genera. 
Reid gives a further characteristic which he 
states can be used to separate Talitrus saltator , 
"the only member of its genus,” from the 
species of Talitroides — some of the flagellar 
segments of the second antennae of T. saltator 
are toothed. 
I find myself most in accord with the view 
expressed by Ruffo (1947) who points out 
that terrestrial and littoral species occur in 
other genera ( Orchestia , Talorchestia). If Tali- 
trus and Talitroides are going to be separated 
on what, because of the scanty morphological 
differences, are essentially ecological grounds, 
then logically these other genera should be 
treated in the same way. He quotes, as evi- 
dence of the unreliability of these morpho- 
logical grounds for separation, the case of 
Talitrus gulliveri which is morphologically in- 
termediate between the Talitrus and Tali- 
troides species. In other words, the morpho- 
logical distinctions break down in practice. 
Because of this, he suggests that Talitroides 
be reduced to subgeneric rank to include all 
species of Talitrus living a typically terrestrial 
life, with the pleopods more or less reduced, 
and with the maxilliped palp elongated and 
not rich in spines. 
In this paper I draw attention to the max- 
illiped palp of Talitrus pad ficus n. sp. which 
is also intermediate between that of T. saltator 
and those of the typical terrestrial species, 
serving further to emphasize Ruffo ’s argu- 
ment. If his suggestions are adopted, then T. 
pacificus can be considered as belonging to the 
subgenus Talitroides on ecological grounds. 
This is the course I have adopted. I have 
accepted Burt’s definition of the genus as the 
most suitable in that it adequately defines 
the genus and yet does not unduly limit it. 
Ruffo ’s proposals ensure that the distinctness 
of T. saltator from most other species in the 
genus is recognised without creating genera 
which, in my opinion, are not justified either 
in practice or in theory. 
Key to Species of Talitrus 
1. Maxilliped palp richly spinose; outer 
plate of maxilliped spinose distally and 
along inner margin; pleopods well de- 
veloped; antenna 2 with some flagellar 
segments toothed; littoral 
saltator (Montagu) 
Antenna 2, flagellar segments smooth; 
terrestrial; other characteristics not com- 
bined as above 2 
2. Large inter-ramal spine of uropod 1 with 
terminal spur .3 
Inter-ramal spine of uropod 1 simple or 
absent; peduncle of uropod 3 with 1 or 
2 spines 4 
3. Inter-ramal spine of uropod 1 has small 
needle-like accessory blade at base of 
terminal spur; peduncle of uropod 3 has 
3 spines pacificus n. sp. 
Inter-ramal spine of uropod 1 has no 
accessory blade . decoratus Carl 
4. Peduncle of uropod 3 has 2 spines .... 5 
Peduncle of uropod 3 has 1 spine 7 
5. Pleopod 3 reduced so outer ramus a small 
conical tubercle with single long terminal 
seta, inner ramus a barely recognisable 
rudiment; uropod 1, both rami without 
dorsal spines; telson with 4 or 5 spines 
on each lateral margin .... topitotum Burt 
Not as above; rami of pleopod 3 reduced 
but not less than half length of peduncle; 
uropod 1, dorsal spines on at least one 
