XVlll. INTRODUCTION. 



In completing the eighty-four groups assigned to the Mol- 

 lusca, I have been much indebted to the assistance of Mr. 

 Frederick Price Marrat, a long known and highly esteemed 

 friend, whose intimate and very extensive acquaintance with 

 shells, as also with the perplexing synonyms of conchology, has 

 rendered his services of the highest value. The identification 

 and manipulation of the specimens, within the groups, in the 

 Mollusca, and also in the Coelenterata, has for some time 

 past been almost entirely entrusted to him. In the manipu- 

 lation of the Crustacea and Echinodej^mata, I have been 

 fortunate in having the efficient aid of Mr. John Chard, 

 whose coloured drawings appear with excellent effect in most 

 of the twenty Table Cases. 



The following Synopsis is designed to shew the systematic 

 position and limits of each group. The arrangement in the 

 higher divisions, sub-kingdoms, provinces, and classes, is 

 almost entirely in accordance with the classification adopted 

 by Professor Huxley, and published in The Student's 

 Manual of Geology, by J. Beete Jukes, M. A., F. R. S., 

 1872. The derivations of many scientific names have been 

 given in Greek characters, to avoid the ambiguity inseparable 

 from the use of English letters to express Greek words. 



The Tablets in each group, as a rule, do not refer to the 

 particular specimens exhibited; but in the Synopsis some 

 objects of more than ordinary interest are often specified. 

 Visitors inspecting the Collection have frequently expressed 

 themselves gratified by having their attention called to illus- 

 trations which might otherwise have escaped their notice. 

 To most of the groups have therefore been appended short 

 notes, designed to render the Synopsis in this respect useful 

 as a handbook to the Collection. 



