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XI. A further Contribution to the Knowledge of the existing Ziplnoid Whales. Genus 

 Mesoplodon. By William Henry Flower, F.R.S., V.P.Z.S. 



Received July 31st, 1877. Read November 6th, 1877. 



[Plates LXXI.-LXXIIL] 



IJURING the six years that have elapsed since I communicated to the Society a 

 memoir on the recent Ziphioid Whales (Trans. Zool. Soc. vol. viii. p. 203) very consi- 

 derable additions have been made to our knowledge of the group. Instead of being 

 so rare as was then supposed, since the attention of naturalists resident in our colonies 

 has been directed to the importance of losing no opportunity of securing such specimens 

 as accidents of wind and waves may cast upon their shores, it has been proved that in 

 the seas of the southern hemisphere these Whales exist in considerable numbers both as 

 species and as individuals, and that one species at least is gregarious, having been met 

 with in two instances in " schools " of considerable numbers. 



On the other hand, no remarkable deviations from the forms abeady known have 

 been met mth ; and all additional information as to their osteology has fully confirmed 

 the value of the division of the Ziphioid Whales into four distinct types or genera, at 

 that time indicated. With perhaps one exception (to be noticed further on), which 

 presents some signs of transition, all the known individuals lately discovered can be 

 aiTanged without any hesitation either as Hyperoodon, Berardius, Ziphius, or Meso- 

 plodon, as defined in the previous memoir. 



It is in our knowledge of the animals of the last-named genus that the greatest 

 advances have been made of late ; and it is to these that the present communication 

 will chiefly relate. 



Affer examining all the available specimens and published descriptions, I have 

 arrived at the conclusion that evidence exists at present of six distinct specific modifica- 

 tions of this form, of which four inhabit the southern temperate seas. To these I shall 

 have to add two more, although in neither case on evidence so satisfactory as might be 

 desired. The synonymy and habitats of the hitherto known species are as follows: — 



1. M. bidens (Sowerby). 



Physeter bidens, Sowerby, Brit. MisceUany, p. 1 (1804). 



Delphinus {Heterodon) sowerbiensis, Blainville, Nouv. Diet. d'Hist. Nat. 2nd ed. tome ii. p. 177 



(1817). 

 D. sowerbyi, Desmarest, Mammalogie, p. 531 (1822). 

 Delphinorhynchus micropterus, Cuvier, Regne Animal, t. i. p. 288 (1829) ; Dumortier, M^m. Acad. 



Roy. Bruxelles, t. xii. (1839). 

 VOL. X. — PART IX. No. 2. — August Ist, 1878. 3l 



