12 EoPER_, on Biddulphia. 
precede it_, in having no central elevation or constriction of 
any kind, and is the only species, excepting B. turnida, in 
which there are several short submarginal spinous processes. 
The minute structure of the valve itself also differs from the 
preceding species, having the appearance of dots or punctse 
under a low power, but resolvable, with a one -eighth objective, 
into distinct hexagonal reticulations. It differs from B. 
granulata in the more apiculate character of the valves, in 
having six or more submarginal spines instead of two in the 
centre of the valve, and in the absence of the peculiar gra- 
nular structure characteristic of that species. 
6. Biddulphia Bailey ii, W. S. 
Valve imperfectly siliceous, divided into three segments 
by lines joining the angular processes, the central portion 
raised, with two slight median elevations, each armed with 
one or two very long awl-shaped spines ; processes somewhat 
linear, with truncate apices; reticulation diagonal, minute. 
(Plate I, figs. 5 to 9.) 
Marine. In addition to Professor Smith's localities — Caldy, 
Pembrokeshire, Rev. J. Guillemard; Humber, Norman ; 
Barking Creek, Roper; Gorleston, Col. Baddeley; coast of 
Northumberland, Dr. Donkin ; Caermarthen, Okeden ; 
Lymington Harbour, E. Grove; Mobile and Savannah, 
Bailey. 
Si/n. Zygoceiios Mobilensis. Bailey, 1850, Mic. Observ., t. ii, f. 34, 35 ; 
Pritch. Inf., 1852, p. 450. 
Biddulphia Baileyii. W. Smith, 1853, Syn., vol. ii, t. xlv, Ixii, 
f. 322. 
This species differs from all others of the genus in the 
peculiar structure of the valve, which is angular, the central 
portion being raised and comparatively flat, whilst the sides 
are inclined at a considerable angle, the junction of the three 
portions appearing as slightly sigmoid or curved lines on the 
side view, as shown in figs. 7, 8, and 9. This species, like 
B. aurita, is subject to very great variation in form and size, 
so much so, that the specimens in one locality, without 
careful comparison with those from several others, might 
readily be considered distinct from the typical form ; but 
though differing greatly in the proportionate length and 
breadth, in the size of the processes, and length of the spines, 
I feel convinced that all having the imperfectly siliceous 
character, and peculiar angular form of the valves, may safely 
be referred to the same species. The side view of the valve 
has not been given by Professor Smith, but it is almost 
