101 
NOTE ON NEOPLEUSTES BICUSPIS (Kroyer) 
AND NV. MONOCUSPIS (Sars). 
By ALFRED O. WALKER, F.LS. 
In ~ Nature,” vol. 78, p. 36, allusion is made to an 
article by Dr. D. 8S. Jordan in the “American Naturalist ” 
in the following words :—“ Starting with the axiom that 
in any region the nearest representative of a given species 
is to be found, not in the same region or in a remote 
region, but in a neighbouring district separated from the 
first by a barrier of some kind or other, the author points 
out that this law rests,” &c. 
In Chambers’s Dictionary an axiom is defined as 
“a self-evident truth; a universally received principle 
in an art or science.” It is pretty generally understood 
what a Natural Law means. 
I do not know how far the above principle is accepted 
as an axiom or law, but the following fact is very difficult 
to reconcile with it. In April, 1907, I spent a couple of 
hours dredging in the hole near the Britannia Bridge in 
the Menai Straits called Pwll Fanog, in the hope of 
procuring specimens of Nannonyxz spinimanus, A. O. 
Walker, which is only known from four specimens taken 
there by me in April or May, 1894. In this I was 
unsuccessful, bui among other species I took the 
following :—- 
*1. Neopleustes (Paramphithoe) bicuspis (Kréyer), 18 speci- 
mens, d, 2, and young. | 
*2.. N. monocuspis (Sars), 16 specimens, 3, 2, and young. 
*3. N. assimilis (Sars), about 50 specimens, 3, 2 with 
- ova, and many young. 
The specimens of 1 ranged in size from 6°5 mm. to 12 mm. 
9 »? 3°5 » ) oy) 
39 2 be) 2°5 ye) D°5 99 
None of ithe females of 1 and 2 were ovigerous; of 3, 
four or five were. 
*G. O. Sars, Crust. of Norway, ‘‘ Amphipoda,”’ pp. 349-52. 
