400 BULLETIN UNITED STATES GEOLOGICAL SUEVEY. 



catoria" (8°, Haarlem, 1873), especially many of those published in 

 the Dutch language. The titles have, in many cases, been taken by 

 preference from this author, for two reasons: first, they are generally 

 more fully given by him, and with greater regard to literal transcrip- 

 tion, than in many other worts; and, secondly, they are usually accom- 

 panied with references to the particular portion of works, when of a 

 general character, relating to the special subject here in hand. The 

 titles unaccredited may be considered as representing the literary 

 resources in this field of research afforded by the iDrincipal libraries of 

 Cambridge and Boston, circumstances having thus far prevented me 

 from consulting those of other cities. In some cases the sets of period- 

 ical x3ublications have proved incomplete, and in a few cases wholly 

 wanting. To cover these deficiencies, titles of works or papers known 

 to me through citation by authors have been taken from the Eoyal 

 Society's "Catalogue of Scientific Papers," or from other bibliographical 

 sources. In this way it is believed that few pajjers of actual scientific 

 value have escaped record. I have, however, j)roof of the incomplete- 

 ness of this "Preliminary List" in the considerable number of "catch 

 references" still in hand, which are too incomplete for insertion, but 

 which an effort will be made to perfect as opportunity may favor, to be 

 given later, with such others as may be met with, in a contemplated 

 reprint of the present "List." In view of a probable later edition, the 

 author earnestly solicits the correction of errors that may be discovered 

 in the i^resent, and would be glad to have his attention directed to any 

 omissions. 



In regard to the plan of the present undertaking, it may be stated 

 that the titles are arranged chronologically, with an alphabetical 

 disposition of authors under each year. The index to the "List" 

 (the titles being consecutively numbered) will facilitate reference to 

 any particular author or paper desired. In the case of minor papers, 

 the annotations are intended as simply an amplification of the title — 

 in other words, an exi)lanation of the scope and nature of the article 

 cited. In works of a general character, containing brief references 

 to the matter here in hand, the particular portion of the work relating 

 to the subject is stated, with an indication of its extent and importance. 

 In the case of monographs, anatomical memoirc, or special works, the 

 contents are indicated by the transcription of sub-titles, when such 

 occur, and by further amplification when deemed desirable; in other 

 cases by supi^lied sub-headings. Each species formally mentioned or 

 figured is enumerated, with page-references, and in case of figures an 

 indication is given of their nature or bearing. As a matter of conven- 

 ience, the si)ecies are generally numbered with Arabic numerals in 

 heavy type, these showing at a glance the number of species formally 

 treated or recognized in the work or memoir. In the case of old 

 works, or where vernacular names are alone used, the modern current 

 systematic equivalent is frequently indicated. In every instance where 

 such occur, new sj>ecies and new genera are especially distinguished. 



