SOME OBSERVATIONS ON ANTARCTIC CETACEA. 503 



a quickly moving animal in the case of Dr LIOUVILLE, the two animals closely 

 resemble one another in form if they are not actually identical.* 



The markings, however, of Dr LIOUVILLE'S animal and mine are decidedly 

 different. The Balxna specimen is mainly white, and its markings are black 

 rather than brown. The whole head, dorsally as far as the line of the base of 

 the pectoral fins, laterally less far back, thence just past the axilla, and extending 

 back in a central ventral line as far back as the extremity of the pectoral fin, 

 is black, with the exception of the throat. The snout is black, not white, as in 

 Dr LIOUVILLE'S drawing, and so are both upper and lower lips. The tail is entirely 

 black : ventrally this black extends forward to half way between the root of the 

 tail and the vent ; dorsally forward of the dorsal fin, which is itself black, to the 

 middle of the back. All the rest of the body is white. There is no lateral stripe 

 as in the case of Dr LIOUVILLE'S drawing. I am inclined, however, to think that 

 this is a polymorphic form of the same animal, especially as His Excellency W. L. 

 ALLARDYCE, formerly Governor of the Falkland Islands, tells me that his impression 

 of the Falkland Islands porpoise is that it is somewhat striped. Mr LYDEKKER is 

 of similar opinion to myself that the Balaena specimen is like Dr LIOUVILLE'S 

 Lac/enorJtyitchus cmciger, Q. and G. ; but in the absence of the skeleton this 

 determination cannot be absolutely relied on. 



The following is TRUE'S description t of the genus Layenorlynchus and of 

 Layenorlnjnchus wuciger : 



"7. Lagenorhynchus, Gray. 



" Rostrum large and broad. Rostral portion of intermaxillse flat (somewhat 

 convex in obliquidens and electra). Pterygoid bones in contact or separate. 

 Symphysis of mandible short. Teeth variable in size, 22 to 45. Vertebrae, 

 73 to 92. 



" Head with a short, ploughshare-like beak (not distinctly marked off from the 

 forehead in obscurus). Dorsal and pectoral fins moderate, falcate. Caudal ridges 

 very prominent. Sides with two areas of light colour separated by irregular, 

 oblique dark bands. 



" Layenorltyitchiis cruciger (D'Orbigny and Gervais). (PI. xxv. figs. 1 and 2.) 



' ; Beak short, only slightly marked off from the convexity of the forehead. Muzzle 

 to the corner of the mouth, forehead, back, dorsal fin, tail, and pectoral fins black. 

 On the sides, from the eye and base of the pectoral fins to the tail, a broad black 

 band. This band is broadest above the base of the pectoral fin, and decreases in 



* "Cetaces de 1'Antaretique," par le Dr J. LIOUVILLE (Deuxieme Expedition Anhirctique Franfaise, Paris, 1913), 

 pp. 165-179. 



+ " Contributions to the Natural History of the Cetacams : a Review of the Family Delpuinidae," by FREDERICK 

 \V. TRUE, Bulletin of the United States National Museum, No. 36, pp. 168, 170, 171, Washington, 1889. 



