514 MR. F. KITTON ON SOME DIATOMACEJE 
coarser, and the puncta of which they are composed are arranged 
in straight lines reaching from the centre to the cireumference ; 
the processes are also more conspicuous from being less marginal : 
it is, moreover, a truly marine species, frequently occurring in 
dredgings attached to marine Alge. On the former the strie 
are delicate, and the puncta form straight and slightly curved 
lines a short distance from the margin only, the larger portion of 
the valve being closely but irregularly covered with small monili- 
form granules, which sometimes appear to be arranged in rosette- 
like patterns. These differences, together with its freshwater 
habitat, are of sufficient value to constitute a new species, which 
I characterize under the name of ; — 
CERATAULUS SOCOTRENSIS, F. Kitton, n. Sp. 
Frustulo ventro adspectu cylindrico ; cingulo dense punctato ; valvulis 
circularibus vel late ellipticis, leviter bullato infra 2-4 processos margi- 
nales; striis delicatis, prope marginem radiatim, per reliquum superficies 
valvuli compacte sed irregulariter dispositis; setze 3 vel pluræ, in medio 
site. Diametro *0023—:0028 pollic. 
Frustule in front view cylindrical, cingulum very finely punc- 
tate; valves cireular or broadly elliptical, slightly bullate below 
the marginal processes, which vary from 2 to 4 in number; strie 
delieate, radiating near the margin, closely but irregularly dis- 
posed on the remainder of the valve ; three or more short sete 
occur midway between the centre and cireumferenee. Diameter 
‘0023 to ‘0028 of an inch. 
Island of Socotra; attached to freshwater plants. 
The following form, although not a new species, has, I believe, 
only been found in two localities until detected in the Socotran 
gathering, viz. in material collected by Dr. Unger in the island 
of Cyprus, and described by Herr Grunow in ‘ Verhandl. der 
k.-k. zool.-bot. Ges. Bd. xiii. 1863. It was subsequently found 
by Colonel Mason in Belgaum, forming large masses ; in some he 
sent me I found filaments 2 of an inch in length, and exceeding 
the dy of an inch in breadth: in a dry state it has a beautiful 
silvery green appearance. In single frustules it very closely re- 
sembles Synedra Ulna. The frustules cohere very firmly, and 
when treated with strong acids the filament usually separates at 
the connecting-zones rather than where the frustules adhere. 
FRAGILARIA UNGERIANA, Grun., l.c. 
Frustules linear-narrow, with conspicuous marginal puncta, 
