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REPORT 1856. 



44. All existing information with regard to the MoUusca of the Boreal 

 districts of North America and the corresponding portion of North-Eastern 

 Asia, will be found embodied in the two following works : — -" Beitrage zu 

 einer Malacozoologia Rossica, von Dr. A. Th. von Middendorff. St. Peters- 

 burg, 1847:" and " Reise in den Aussersten Norden und Osten Sibiriens, 

 wahrend der Jahre 1843 und 1844, von Dr. A, Th. v. Middendorff. Band II. 

 Zoologie. Theil I. Wirbellose Thiere. St. Petersburg, 1851. Mollusken, 

 pp. 163-464." The author not only describes the results of his own travels, 

 but arranges the discoveries of Eschscholtz (to whose specimens he had 

 access), Mertens, Wosnessenski, and others. The descriptions are very 

 minute and complex, the remarks extremely diffuse, and the references 

 tabulated with consummate learning. Unfortunately, in his comparisons 

 with the British Fauna, he had no better manual than Thorpe's Marine 

 Conchology ; the invaluable work of Messrs. Forbes and Hanley not having 

 been then completed. The first part of the ' Malacozoologia Rossica,' entitled 

 " Beschreibung und Anatomie ganz neuer, oder fiir Russland neuer Chi- 

 TONEN," containing 151 quarto pages, with 14 plates, consists of an account of 

 21 species, of which 17 inhabit the Pacific shores. To an account of the prin- 

 cipal form. Chiton Stelleri, 59 pages are devoted. All who study or describe 

 species in this very interesting and difficult group, will do well to consult as 

 much as their time allows of this comprehensive treatise. It is to be regretted 

 that in the principles which have directed his classification, he has confined 

 his attention to so limited a number of types; and, however burdensome to 

 the memory may be the very numerous genera of modern writers, the sub- 

 genera, sections, subsections and divisions found necessary to accommodate 

 only twenty-one out of the many hundreds of known species, by no means 

 lessen the inconvenience. Thus to descend from genus Chiton to species 

 Pallasii, the Middendorffian student has to master the following phraseology : 

 " Chiton-Phsenochiton-Dichachiton-Symmetrogephyrus (B. Apori) Pallasii." 

 The following are the Pacific species; the synonyms being those of Midden- 

 dorff, unless enclosed in [ ]. 



Part I. 



