O34 Prof. T. Rupert Jones— Wealden Ostracoda. 
is extraordinarily long, the intervals between the septa, at first short 
and irregular, become during the progress of the growth, unusually 
long. The siphuncle is narrow and straight, generally situated near 
the ventral surface. The decollation is oblique, following the direc- 
tion of the septa. 
The commencement of the Ascoceras stage is partially indicated 
by the increased distance between the septa. Very important 
changes in the shape of the animal, and probably also altered 
functions must have supervened, when its shell, thus rapidly, as it 
were, developed the very abnormal Ascoceras form. The septa were 
pushed up along the dorsal, and greatly depressed along the ventral 
side, where also the cochleate or bullate siphuncle is placed. In no 
other genus of the Cephalopoda are such aberrant septa developed. 
The most curious feature is that, with the exception of the lowest or 
oldest one, they are all incomplete, having a large lacuna in their 
central part on the dorsal side. They have thus been secreted only 
along the interior wall of the shell, leaving an empty space between 
their thin linings. Hence the different aspect they present in many 
of the figures in various publications. Thus they are continuous 
along the outside of a cast of the interior (Barrande, Céphalopodes, 
~ pl. 98, fig. 1), and truncated, discontinuous and resting on each 
other in a median, longitudinal section (Barr. l.c. pl. 93, fig. 4). 
The discovery of these Gotland specimens of Ascoceras fully con- 
firms the views of Bronn, expressed in 1855, at a time when neither 
he nor any one else had seen perfect specimens, as to the relationships 
of this genus. Barrande stated that Ascoceras possessed only a single 
deciduous chamber below the “lateral chambers,” and he regarded 
the genus as the prototype of Nautilus. Bronn, on the other hand, 
invited by Barrande to give an opinion on the subject, suggested that 
if Ascoceras, at an early stage, threw off a portion of its growth, 
consisting of regular air-chambers with a siphuncle, then “ Ortho- 
ceras is rather to be designated as the early stage of Ascoceras” 
(Neues Jahrbuch fiir Mineralogie, etc., 1855, p. 288, footnote **). 
JII.—Osrracopa From THE WerALD Cuay oF THE IsLE or WIGHT. 
By Prof. T. Rupert Jonzs,! F.R.S., ete. 
ConTENTSs. 
- Cypris cornigera, sp. nov. Woodcuts, Figs. la-lf, p. 636. 
. Candona Mantelli, sp. nov. Woodcuts, Figs. 2a, 6, p. 536. 
. Cypridea Valdensis (Fitton). 
- Cypridea Dunkeri, Jones. 
Cypridea spinigera (Sow.). 
. Cypridea Austeni, Jones. 
Darwinula leguminella (Forbes). 
- Cyprione Bristovii, Jones. 
. Metacypris Fittoni (Mantell), 
OME new species having been found in the Isle of Wight during 
the lately renewed examination of its geology by the Geological 
Survey, and the known Wealden species of that island not having 
OAOIDOP cob 
* Mr. C. D, Sherborn, F.G.S., has kindly assisted the writer in the examination 
of these Ostracoda. 
