APPENDIX. 
Dvrine the progress of this work through the press, we have 
been enabled to submit many of the animals referred to in 
its pages to a careful re-examination, which has in some few 
instances shown that our original impressions were partially 
incorrect, and in others has caused us to modify our opinions 
to a greater or less extent. The results of such observations 
as were made too late to be incorporated in the body of the 
work, are contaimed in the following Appendix. 
SCROBICULARIA PIPERATA. 
(P. 138.) 
Exmouth, July 1854. 
As my original notes upon this animal were but scanty, I 
have gladly embraced an opportunity of making a fresh ex- 
amination of its structure, particularly as it presents a very 
unusual configuration of the branchize and palpi. 
I find that these organs are of the palest brown, with a 
shght red cast. The palpi are regularly triangular, pointed, 
enormously large as regards length and breadth, compara- 
tively smooth without, and strongly striated within. There 
is only a single branchia on each side the body, of a broad 
triangular shape, very thick, fixed by the longest side to the 
posterior dorsal range, with the angular point vertical to the 
ventral line; it is divided diagonally, by a subcentral narrow 
groove, into two subtriangular portions, whereof the one 
nearest the dorsal slope is usually the least. Instead of one 
part folding on the other, as in the regular two-leaved bran- 
chiz, it is thrown back and pmned to the posterior dorsal 
slope, forming one moderate branchial plate, certainly not much 
