IV PREFACE. 



received in preparing particular portions of the work ; and es- 

 pecially from Mr. T. Davidson, FGS. in the investigation of the 

 Brachiopoda ; Mr. J. W. Wilton of Gloucester, in reference to 

 the lingual dentition of the Gasteropods ; Mr. T. Huxley, FES. 

 for the revision of the chapter on the Tunicata ; and to Mr. 

 Albany Hancock, of Newcastle, for advice and information, often 

 only to be obtained by new and careful investigations. 



To Mr. H. Cuming he is indebted for the use of books and 

 specimens ; to the officers of the Museum, especially to Dr. 

 Baird, and Mr. Waterhouse, for encouragement and sympathy ; 

 and to the Council of the Geological Society (1858-4) for the 

 expression of their approval by the TVollaston award. 



The wood-cuts have been principally executed by Miss A. 

 N. Waterhouse of ]\Iarlborough House, from original drawings 

 by the author ; and although printed from stereotypes they have 

 the advantage of accurately representing what was wished to be 

 shewn. 



The engravings of Mr. Wilson Lowry, speak for themselves ; 

 many of the figures are from the specimens in his cabinet ; 

 and the interest he has taken in the work will be seen in the care 

 with which the technical characters of the shells are expressed. 



Barnsbury, March, 1856. 



Directions to the Binder. 



In blading the com])lete work, the Tables of Contents of the three Parts 

 should be placed together at the beginning. 



The Plates should be arranged in pairs, face to face, with the Explanation 

 opposite to each. 



