VI 



uutlior, were ft lii^lily welcome atliU'iidiiiii. Pacific sliells are ln-sides <lescril>eil 

 by Car lauter in the rroceedings of the California Aaideniy of natiinkl scienws, 

 whilst Gould's publications, except those alremly mentioned, are chiefly cont4iined 

 in the Boston Proceedings of the society of natunil liistory, cpioted in some 

 instiinces in this memoir. 



As the natnre of the fauna descril»e<l will show, the com|<irisüu with 

 Atlantic shells was of a much gn-ater ira|x>rtance than, iHjrhap«, could have been 

 exiK-ctetl. This was done chiefly with the aid of Forlx-a and Ifauley's british 

 Mollusca, 4 volumes, London, 1853, of Jejiiyn british Concholojjy, 4 »olumes 

 London, 1867 (year of last publication), but also of Oould-Uinneys report on 

 the Invertebrates of Maasjvchusetts, 2d e<l., Molluscji, Boston 1870, Stimpsou's 

 revision pj). Boston 1857, Tryon's American nmrine Concholoj^y, Philadelphia 

 1873, W'ciukaiifi's Conchylien des Jlitteimeeres, J volumes, 18G7 an<l ISG8. 

 But it was quite as importiint to com[)are the shells in question with other fossil 

 shells; and for this jiurjwse the 'Crag-Mollusca,' descrilHjd (and figunxl) by 

 S. Wood in the repnis of the Paleontolof^ical Society of Ixin<lon (in two sections, 

 one contained in 3 dilferent numliers, with two supplements, the tirst of which 

 has also 2 parts, the whole published within the years 1847-1879) were m(«t 

 essential. The sulKijHjnnine fauna could not \>e consulted in the original publi- 

 cations; but this was the case again with a great i)art of the Geniian j>iii)er8 on 

 the fossil be<ls of Mayence, Vienna, Oassel, S<iellingen, on the Mecklenburg 

 tertiary layers, &c., as well as with Nyst's accounts of Belgian fossils. Gddfu»»' 

 Petrefivcti Germaniaj — of course— were sometimes of great ns<.'. — As the Brac-hio- 

 poda were added to the true mollusca, the {»ajiers of iJaiidson, abo^e all Ids 

 paiier on Jajmuese recent Brachiopoda, from the ' proceedings of tlie Zoological 

 Society of London,' April 18th, 1871, page 300-312, and pi. 30 and 3J, were 

 consulted. 



With the aid of all these books— and many others used on different occa.sious, 

 all of which need not be mentioned — I feel I have only made a preliminary step 

 in an investigation which, though offering very great difTiculties, is of such 

 imjiortjince that it seemed to me to require immediivtc treatment. A further 

 delay would, alK)veall, have been difcadvantageous to the students of the l)aigal<u; 

 I nee<l. therefore, make no ai)ology for this Memoir. 



I cannot omit to call the attention of the rea<ler t(j the clever way in which the 

 Japanese artist, Mr. II. Hirauclii, has done his work in designing the illustrations, 

 and chiefly a certain number of the pliocene shells. Though — among the more fre- 

 quent, or otherwise imjtortant sjiecies — only such siwcimens were selected, as were 

 well preserved, yet the task set to him was so entirely new, that the difficulties 

 he was to sunnount arc not to be undemitwl. Much of whatever is excellent in 

 the appearance of the book is due to the successful execution of his work. As to 

 the printing &c, it may he called in this case as well as in the preceding memoirs 

 'surprisingly el>gjiiit and correct. ' I seize this oiqxirtunity of expressing my U-st 

 thanks for all the aid ^'iven jne in this dia-ction by the Presidents of the Daignku. 



