RoPER_, on Biddulphia. 
L7 
his works. The description and locality from which this 
was obtained_, induce me, however, to adopt his name rather 
than add another to the already overburdened list. 
The perfect frustules of this species are not uncommon, 
but I have only met with a single detached valve showing 
the S.V., in which there appears to be a slight depression in 
the centre as shown in fig 22, from which the small spines 
are absent. 
This species is readily distinguished from any other of the 
genus by the peculiar subcapitate form of the processes, and 
from the so-called apertures being at right angles to the 
suture of the valve instead of being parallel with, or slightly 
inclined towards it. 
11. Biddulphia turgida, Ehrenberg. (sp.) 
Valve elliptical or suborbicular, minutely reticulated, with 
small spines scattered at irregular intervals over the surface, 
occasionally furnished with a submarginal circlet of short 
obtuse spines, and with two long submedian spinous processes. 
Angular processes large, linear, and truncate. (Plate II, fig. 
23.) 
Marine. Neyland, near Haverfordwest; Okeden. Milton, 
Pembroke Harbour, and Pater, Milford Haven; Roper. 
Menai Straits ; Shadbolt. Hudson Pviver and West Point ; 
Bailey. 
Syn. Ceeataulus tukgidus. Bailey, 1850, Mic. Obs., t. ii, f. 26, 27; 
Ehr. Ber. Proc, 1843, p. 270; Pritch. Inf., 1852, p. 330. 
Biddulphia turgida. W. Smith, 1856, Synopsis, vol. ii, t. Ixii, 
f. 384. 
The figures and description of this species in the ^ Synopsis ^ 
give a very correct idea of the fine specimens first discovered 
by my friend Mr. Okeden, but in order to include the smaller 
forms since found in a living state on the coast, I have 
slightly altered the specific characters. Professor Bailey 
states that he met with it, in 1 843,'^ in a living state, and 
forming zigzag chains as in other species of the genus. 
Since the publication of the second volume of the ^ Synopsis,^ 
I have met with it in two gatherings from the neighbourhood 
of Pembroke, and Mr. Shadbolt also records it from a 
gathering made at the Menai Straits.f The connecting 
membrane in this species is peculiar, in almost always 
showing a sigmoid flexure on the front view of the perfect 
frustule. The very large and prominent angular processes 
readily distinguish it from all the other species of the genus. 
* * Mic. Observ.,' by Smithson. Instit., vol. ii, p. 39. 
t ' Mic. Journ.,' vol. vi, p. 123. 
VOL. VII. C 
