Dall.] 44 [December 6, 



A genus Limnorea Dyb. is proposed, with two subgenera Leucosia 

 and Ligea Dyb. ; for the first four new species are described and one 

 referred by Gerstfeldt to the genus Hydrolia is added to them. To 

 the second subgenus eight new species are referred. They appear to 

 be allied to Littorinella. As not unfrequently occurs in memoirs 

 where the author's attention has been chiefly devoted to anatomical 

 details, the nomenclature and systematic relations appear to have 

 been somewhat neglected. At least this is the most satisfactory man- 

 ner of accounting for certain deficiencies to which this note is chiefly 

 directed. The genus Benedictia appears to be well founded and 

 homogeneous, but before it can be definitely accepted a careful com- 

 parison is necessary between the Lioplacince and the form referred 

 to. Lioplacodes Meek (1864), offers some points of resemblance. 

 This comparison is especially needed to test the validity of the au- 

 thor's proposal to make Benedictia the type of a new family allied 

 more nearly to the Hydrobiince of Stimpson than to the Viviparidce. 

 This view is doubtful when the resemblance of the dentition of at least 

 one of the species to that of Lioplax is noted, and in the absence 

 of any figure of the operculum of Benedictia, which would seem by 

 the description to be related to that of Lioplax. 



The genus Limnorea is also proposed as type of a distinct family, 

 whose validity it is not at present practicable to test in the absence 

 of details in regard to apparently allied groups, which have been 

 raised to generic significance by different authors within a few years. 



The names adopted by the author unfortunately have been already 

 preoccupied in Crustacea for many years in several cases, as has al- 

 ready been pointed out in a review of the memoir by Yon Martens. 1 



Limnorea by Peron and Lesueur in Acalephs (1809), in Polyps by 

 Lamoroux (in 1821), and by Leach and Dana in Crustacea. 



Leucosia was used for a valid genus of Crustacea in 1798. 



Ligea, under the form Ligia, is also preoccupied by Fabricius, and 

 by Duponchel in Lepidoptera. These facts were recognized by Mar- 

 tens, who unfortunately did not observe that Leucosia, even if not 

 preoccupied, would necessarily fall, from the fact that no subdivision 

 had been left by Dybowski to receive the typical forms of his genus 

 Limnorea, and who also neglected, as had the author he was review- 

 ing, to mention any types of the several groups. Martens proposes 

 for Limnorea the generic name Baicalia (mel. Baikalia) and for Leu- 



* Jahrb. Deutsch. Malak. Ges. 1876. Heft. II, p. 181. 



