Geographical Distnhution of the Qenus Diaptomus. 177 



them (fig. B). It will be noticed that the new species has 

 " scaphoid spicules " ahuost as well marked as those of X, 

 anceps^ but these are wanting in X. setacea. For the 

 present I content myself with calling attention to this fact, 

 which must, obviously, be borne in mind when the questions 

 are asked, Are scaphoid spicules of generic value ? and Is the 

 genus Xiphigorgia a natural one? 



Hab. St. Thomas, West Indies. Coll. B.M. 



XXII. — On the Geographical Distribution of the Genus 

 Diaptomus. By MM. J. de Guerne and J. Richard*. 



Recent works relating to lacustrine faunas have called atten- 

 tion to the freshwater Calanida?. These Copepods, and 

 especially the DiajJtomi, are much more numerous in species 

 and much more widely distributed than is generally supposed. 



If we except some forms recently described f most of the 

 common types have been confounded and indicated under the 

 name of Diaptomus castor. From this it results that the 

 geographical distribution of these species cannot be esta- 

 blished in a complete fashion. However, the numerous data 

 which we have been able to bring together and the kind 

 assistance of several zoologists :j: enable us, leaving out of con- 

 sideration all doubtful observations, to trace an outline of the 

 distribution of the genus Diaptomus on the surface of the 

 globe. 



The European species that we admit §, not taking into 

 account purely nominal or insufficiently described forms, are 

 fifteen in number. Among them six species are known only 

 from a single locality in the extreme north, the centre, 

 or the south of Europe (Lapland, Germany, Russia, Spain). 

 Three others appear to be peculiar to the mountainous regions 

 of Central Europe, but have never been met with together, 



* Translated from the < Comptes Rendus,' July 2, 1888, pp. 47-50. 



t See in tlie ' BulMin de la Societe Zoologique de France,' vol. xiii. 

 (February and June 1888), the descriptions of eight new Diaptomi, by 

 MM. Richard, LUljeborg, Poppe, and Richard and de Guerne. 



X In this connexion we have to thank particularly Profs. Lilljeborg, 

 G. O. Sars, and Wierzejsky, and M. Poppe, who have been kind enough 

 to furnish us with little-known types or with descriptions of unpublished 

 species. 



§ See our " Revision des Calanides d'eau douce," which will shortly 

 appear in vol. i. of the ' Memoires ' of the Zoological Society of France. 



Ann. & ]\lag.N. Hist. Ser. 6. f'o^. ii. 12 



