Dr. Wallich, on the Polycystina. 
75 
PiNNULARIA. 
Pinnularia Hartley ana, n. sp., Grev.— Large ; valve broadly 
linear, somewhat inflated in the middle and at the rounded 
©nds ; costse radiate, leaving a wide median space, as well as 
a transverse fascia extending to the margin. (Fig. 30.) 
Hab. In a sluggish stream at Cavalla, Liberia ; Rev. 
Benjamin Hartley. 
A splendid new species, belonging to a small sedition of the 
genus characterised by the transverse smooth fascia in the 
middle of the valve. It is longer, although less robust, than 
P. cardinalis, and is remarkable for much narrower striie than 
are found in the larger Pinnularia;, the number being about 
20 in -€01'', The length of the frustule is -0090"; breadth 
in the middle '0013''. 
For the gathering containing this fine diatom I am in- 
debted to the kindness of my friend the Rev. Benjamin 
Hartley, now resident in Liberia. It is associated with 
Synedra biceps, NitzscMa obtusa, Pinnularia mesolepta, Hi- 
mantidium gracile, Navicula crassinervia, Eunotia diodon, &c. 
I trust that the success which has attended his first collection 
in Liberian waters will induce him to continue his researches. 
On the Structure and Affinities of the Polycystina. 
By O. C. Wallich, M.D., F.L.S., &c. 
(Read May 10th, 1865.) 
Although our knowledge of the characters and true posi- 
tion in the animal kingdom of the Rhizopods has of late 
years been largely augmented through the combined labours 
of both Continental and British naturalists, it is a singular 
fact that the Polycystina, so long regarded by the micro- 
scopist as favorite objects, should have been, comparatively 
speaking, neglected ; and that, up to the present period, no 
attempt should have been made to reduce the family, as a 
whole, to anything like systematic order. 
It shall be my endeavour, on the present occasion, to per- 
form this task to the best of my ability. But I would 
take the opportunity of stating at the outset, that it forms 
no part of my purpose to describe species. I shall accord- 
ingly restrict myself to indicating what appears to me to be 
the natural position of the Polycystina amongst the other 
