48 
CLASS I. — ORDER I. 
oval, oblong, and projecting ; opening marginated, and 
nearly pentagonal. 
On the Fucus natans. 
TOOTHED. 
20. Flustra dentata . Incrustation; but fre- 
quently foliated; cells nearly oval, shining, and 
toothed at the border. 
European seas. 
SQUARE. 
21. Flustra quadrata. Incrustation; cells form- 
ing a long regular quadrangle with even borders. 
On the Fucus pyriferus. 
Variety on the fossils in the vicinity of Paris. 
TRIACANTHOUS. 
22. Flustra triacantha . Incrustation; cells oval 
or round, with two side thorns on the upper part, and 
one on the lower. 
On the Thalassiophytes of Australasia. 
MANY-TOOTHED. 
23. Flustra multidentata . Incrustation ; cells 
large and nearly round ; opening garnished with many 
long unequal teeth. 
On the fucus of Australasia. 
LANIGEROUS. 
24. Flustra eriophora . Incrustation; cells very 
small, alternate, round at the summit, covered with 
unequal and numerous hairs. — Plate 1. fig. 5. 
On the fucus of Australasia. 
