ON OSTRACODA NEW TO GREAT BRITAIN. 143 
Polygonum arenastrum, Jordan. — Stems solid, upright, 
strong, crowded, nearly smooth in the internodes. Leaves long- 
ovate, seldom exceeding half an inch long, length to breadth 
about 4 to 1. Stipules much lacerated, as in rurivagum, but 
dark coloured and shorter than the flowers. Flowers pale, 2-4 
in each axil, nearly sessile. Height about six inches. 
Totally different in habit from the other forms. A little bush, 
with stout and crowded erect stems, the leaves and flowers 
crowded and imbricated, both withering and falling off soon 
after flowering, so that the base of the stems are usually bare 
(more especially if the plant be growing in sand) save that a 
circle of much divided brown stipules surrounds each of the 
closely-set joints. 
A. Polygonum which I gathered on the West Hartlepool 
ballast hills in 1860, was referred, but with doubt, to arenastrum 
by M. Boreau. The plant above described, and which is prob- 
ably the typical arenastrum, I have found this year abundantly 
about Seaham.* 
XXVII.—On species of Ostracoda, found in Norihumberland and 
Durham, new to Great Britain. By the Rev. Atrrep MERLE 
Norman, M.A. 
It is strange that so few British Naturalists should have up to 
the present time studied the Entomostraca. Surely this can 
only be the case because they are ignorant of the extremely in- 
teresting field of search which lies open to them, and the maryel- 
lous diversity in Morphological and Physiological characters which 
this lower division of the Crustacea exhibits. This is not the 
place to give details on the subject; but in the hope of inciting 
others to enquiry I cannot help briefly alluding to some of the 
anomalies and other points of especial interest which are pre- 
sented to us in the history of the three orders, Cladocera, Ostra- 
coda, and Copepoda. Those who would follow up the hints here 
given are referred to Dr. Baird’s “ History of British Entomos- 
* A set of these plants has been presented to the Natural History Society of Newcastle- 
on-Tyne, at whose Museum they can be referred to by members of the club. 
