18 
Shadbolt on Neio Forms of Diatomacece. 
are arranged across each other. The smaller of the two spe- 
cies (fig. 16), D. simplex, has but one central inflation, and the 
lateral expansions are symmetrically placed so as to give each 
valve the appearance of a sort of mitre or head-dress. It is 
marked with numerous well-defined dots or cells (?). The 
second species, D. margaritifera (fig. 17), has, besides the 
two lateral expansions, three intermediate inflations, the cen- 
tral one being considerably the largest, and the whole is 
covered by numerous pearl-like eminences similar in aspect to 
those so common in Cosmarium and other DesmidieoB. In 
both species the union of the two valves is marked by a sort 
of projecting band, which completely encircles the frustule. 
In addition to those I have described there are very many 
other forms already familiar to observers of the Diatomece^ 
and doubtless some new forms which 1 have overlooked. I 
am well aware that the present is a most imperfect sketch of 
a highly interesting gathering, containing, as will be shown 
by the follovving siimmniy, no less than 55 species, of which 
20 are certainly new, and in addition 4 forms of Sponge 
spicula. 
Species. Species. 
Bacteriastrium 
Calophyllum 
Triceratium . 
Pleurosigma . 
Amphitetras . 
Actinophaenia 
Eupodisciis 
Asterolampra . 
Denticella 
Campylodiscus 
Climacosphajnia 
Naviciila 
Stauroneis 
rinnularia 
Nitzschia 
G ramm atophora 
Tabellaria 
Striatella 
Zygoceros 
Acnanthes 
Cocconeis 
Doryphora 
Podoaphasnia . 
Synedra 
Coscinodiscns . 
Tryblionella . 
Meloseira 
Biddulphia 
Epithemium . 
Dictyochas 
of whicl: 
are certainly new 3 
1 
5 
2 
2 
1 
1 
2 
1 
1 
20 
And 4 forms of Sponge Spicules. 
55 
