BIBLIOGRAPHY. 23 



As the numbers for the different counties reach 50 forms 

 or more, it is intended to publish the Usts, beginning, of course, 

 with those for which the largest amount of work has been done. 

 The publication of the list for Mid-west Yorkshire has already 

 been authorised. 



The Recorder has, in conclusion, only to hope that 

 conchologists — and especially members of the society — will 

 co-operate in the work by forwarding specimens (accurately 

 labelled, with locality and other particulars) from their own or 

 any district which they may collect in. And they may be 

 reminded, that of the 149 counties arid vice-counties into which, 

 for this purpose, the British Isles are divided, there have as yet 

 been only authenticated records of this kind for 49 of them, 

 leaving no less than 100 counties — equal to two-thirds of the 

 whole number — in the position of never having been represented 

 at the meetings by a single moUusk. 



BIBLIOGRAPHY. 



Manual of Conchology, structural and systematic. — 



With illustrations of the species by Geo. W. Tryon, junr., 

 Conservator of the Conchological Section of the Academy of 

 Natural Sciences, Philadelphia. Parts xvii. and xviii. 



Part xvii. commences the fourth volume of this compre- 

 hensive work, and is devoted to the families Marginellidse, 

 Olividse and Columbellidae. The family Marginellidas is divided 

 into the genera Erato Risso, with eighteen species, and 

 Marginella Lam., with 230 recent species, the majority of 

 which are from the Caribbean region. The author deals 

 exhaustively with the arrangement and classification of this 

 group, and also gives in detail the views of the different authors 

 who have written upon the subject. The arrangement adopted 

 is that proposed by Weinkauff in his Synonymic Catalogue of 

 the genus, published in the Jahr. d. deutsch. Mai. Gesel. — two 



