Critical Studies on some Odontoceti. 179 



sphere. Prof. G. O. Sars has obtained in Christiania a still 

 undescribed Diaptomus by cultivating muds brought dry from 

 Australia. 



This fact possesses much interest as regards the geogra- 

 phical distribution of the genus. It indicates a ready means 

 of dissemination and enables us to explain the presence of a 

 Diaptomus in considerable quantities in the neighbourhood of 

 Oran [vide supra), in chotts which remain dry during the 

 greater part of the year. 



In connexion with this we may also call attention to the 

 fact that certain Diaptomi appear to adapt themselves easily 

 to waters of very different degrees of saltness. Dr. Raphael 

 Blanchard has collected the species already mentioned in 

 water which held in solution as much as 29*15 grains of 

 chlorides per litre on April 1, 1888. At the same time this 

 Copepod occurred in water containing not more than 14*04 

 grains of chlorides per litre. Analogous facts have been pre- 

 viously noted with regard to D. salinus and D. laticeps. 

 This latter species lives as well in the fresh waters of Scan- 

 dinavia as in the Salzigersee, near Halle, the water of which 

 contains 0*15 per cent, of salts. 



Thus, the genus Diaptomus may be regarded as cosmo- 

 ])olite. In all probability future researches will lead to the 

 discovery of new species in different parts of the globe, and 

 will enable us to ascertain a much more extended geographical 

 distribution for the described forms. 



XXIII. — Critical Studies upon some Odontoceti of the Genera 

 Tursiops, Orca, a7id Lagenorhynchus. By M. Chr. 

 LiJTKEN*. 



I. 



About twenty years ago Prof. Steenstrup acquired at Trieste 

 the skin and skeleton of a small Dolphin captured in the 

 Adriatic. ■ On the amalgamation of our natural-history 

 museums these two specimens passed into the Cetological col- 

 lection of the University, and were mounted there, in 1865 

 and 1866, under the name of Delphinus parvimanus. In 



* Translated from the ' Kongelige Danske Videnskabernes Selskabs 

 Skrifter, naturvidenskabelig og mathematisk Afhandlingar/ ser. 6, vol. iv. 

 pp. 391-397. The Danish memoir of which this is an Abstract occupies 

 54 pages (pp. 337-390), and is ilhistrated with two plates and a con- 

 siderable number of woodcuts. 



12* 



