G. FLUSTRA. 
45 
PEAR-SHAPED. 
3. Flustra piriformis. Foliaceous and dichoto- 
mous ; summits truncated ; cells formed like a pyramid, 
very sharp at the bottom ; height about one decime- 
tre ; width in the middle of the branches from two t© 
four millimetres. — Plate 1. fig. 4. 
Australasia. 
CERANOIDOUS. 
4. Flustra ceranoides. Flower-like and dichoto- 
mous ; summits bifid ; extremities obtuse ; cells long ; 
mouth almost linear, with the border rolled over; 
height from five to eight centimetres ; width in the 
middle of the branch two or three millimetres. 
Australasian sea. 
BOMBYCTNOUS. 
5. Flustra bomhycina . Plant-formed, with ob- 
tuse divisions, dichotomous or trichotomous ; cells 
rounded ; foot root-formed. 
On the coast of Calvados, a reef of rocks bordering 
on Normandy ; and also said to be found in the Indian 
and American seas. 
flaxen. 
6. Flustra carbasea. Foliaceous, dichotomous, 
and obtuse at the summit ; cells long and formed py- 
ramidically. 
On the coasts of Scotland and Calvados. 
CHARTACEOUS. 
7. Flustra chartacea . Foliaceous, digitated, and 
truncated at the summit ; cells four-sided. 
Coasts of England and France. 
