INTRODUCTION. 
Xlll 
large collection of examples of Fishes sent home by 
officers of the Medical Staff, and which still remain 
unopened, in the Fort Pitt Museum at Chatham ; but 
I am not without hope that these may shortly undergo 
comparison with the drawings which exist of each, and 
that this branch of the island fauna may at last attract 
the attention to which its richness so eminently en- 
titles it. 
In the department of Entomology much has already 
been achieved ; but an extended area still invites future 
explorers ; and one which the Notes of Mr. Walker 
prefixed to the List of Insects in this volume, show to 
be of extraordinary interest, from the unexpected con- 
vergence in Ceylon of characteristics heretofore sup- 
posed to have been kept distinct by the broad lines 
of geographical distribution. 
Eelative to the inferior classes of Invertebrata very 
little has as yet been ascertained. The Mollusca, espe- 
cially the lacustrine and fluviatile, have been most 
imperfectly investigated; and of the land-shells, a 
large proportion have yet to be submitted to scientific 
examination. 
The same may be said of the Arachnida and Crus- 
tacea. The jungle is frequented by spiders, phalangia l , 
and acarids, of which nothing is known with certainty ; 
and the sea-shore and sands have been equally over- 
looked, so far as concerns the infinite variety of lobsters, 
crayfish, crabs, and all their minor congeners. The 
1 Commonly called " harvest-men." 
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