238 Transactions of the Boyal Microscopical Society. 
COCCONEIS. 
1. G. notata (P. Petit). Valves ovate, median line sigmoid, 
central nodule dilated into a smooth band (pseudo-stauros) reaching 
the margin and terminated at one margin by a circular hyaline 
enlargement. Striae transverse, very close, subradiant, and finely 
punctate, reaching median line. Length 26 ya 4, breadth 13 ya 6.* 
Lyell’sBay. PI. XIY., Fig. 1. 
2. C. australis (P. Petit). Valves dissimilar, small sub- 
orbicular, the inferior (Fig. 2h) having a sigmoid line. Striae 
longitudinal, close. The superior valve (Fig. 2c) smooth, but fur- 
nished with short distant marginal costae (closely resembling the 
canaliculi of the Surirellae). Length 26 fju 4, breadth 24 yu 2. 
Lyell’s Bay. PL XIV., Fig. 2. 
3. Raphoneis fasciolata, var. australis (P. Petit). This form 
shows characters differing from the type. The rows of granules 
increase in length as they approach the centre, producing a very 
marked contraction in the smooth space occupying the centre of the 
valve. This variety is very variable in shape and size, its length 
varying between 28 6 and 55 /uu. 
LyelLs Bay, where it is very abundant, but it does not occur 
in other localities. PI. XIV., Fig. 6. 
Hyalodiscus, Ehr. 
(Cleve emend. : Diatoms from the Arctic Sea, p. 4.) 
Note on the Genus. — M. Cleve has already verified the affinities 
of all the discoid species with a central fracture or umbilicus. 
These he has correctly united in a single genus Hyalodiscus of 
Ehrenberg. We have moreover remarked, that in all the species 
placed in Podosira the zone is curved in an opposite direction to 
that which exists in P. Montagnei. In examining H. hormoides 
(p- hormoides, Ktz.) living, we have seen that the endochrome 
has nothing in common with that of the true Podosirae ; it is 
granular, as it is in the Melosirae to which it belongs. The endo- 
chrome in H. hormoides forms a single plasmatic layer with four 
lobes, and always resembling in disposition the endochrome of 
Achnanthidium ; it is only in contact with one side. These 
characters clearly indicate that H. hormoides ought to be classed 
with the Achnantheae if we follow the system of classification pro- 
posed in our list of diatoms,! and it is probable other species of the 
genus exhibit the same peculiarities if we had the opportunity of 
studying them. 
4. jk. maximusX (P. Petit). Valves discoid, very large, central 
* 1 yu = ‘0001 of a metre, ’001 of an English inch = 25 339. 
t See ‘ M. M. J.,’ vol. xviii. p. 10, 
X Eiilenstein has previously published a species which he has named maximus. 
See Habirsbaw’s ‘Catalogue of the Diatomacea).’ 
