38 E. LÖNNBERG, CONTRIBUTTONS TO THE FAUNA OF SOUTH GEORGIA. 



been measured by True (20), but he quotes Struthers who says: »The hairs are 

 fullv 4 inclies in length, some 6 inches.» The greater development of the baleen, 

 as well the blades as the bristles, of the southern Humpback are no doubt of biolo- 

 gical importance and stånds in connection with the condition of the food which, 

 Sörling says, consists entirely of Euphausiids (»kril»), while the northern race also 

 feeds on fish (Mallotus, Gadus saicla according to Lilljeborg). 



The dorsal fin is low, and at least in the foetus not falcate. 



SöRLiNG has not observed that the dorsal crest of the caudal region of the 

 southern Humpback is denticulated as Racovitza (18) has described and figured 

 from the western side of Graham land. 



The shape of the pectoral fin of the foetus with its tubercles is presented on 

 Pl. IX. It appears to agree essentially with the same of the northern race. 



As True (20) has shown for the northern Humpback, the flukes are already 

 in the foetal stage notched and fringed by a series of processes with emarginations 

 between them. When the same appearance of the flukes is found in the adult, it is 

 evident that it cannot be ascribed to injury but is a natural character retained from 

 the foetal stage. The same is proved with regard to the foetus of the southern 

 Humpback by Pl. IX. 



Sörling has taken some measurements of a young Humpback and two foetuses 

 as the following figures show: 



Young cT sbot Foetus ef", the Foetus 9, the 



Distance from tip of snön t to b. i nd: margin of the niiddle of candal fin 



in a straight line 



Distance from snont to begiiiiiing of dorsal fin 



Distance from snont to end of dorsal fm 



Distance from anterior börder of axilla to tip of pectoral tiu . . . . 



Length of base of dorsal fin 



Distance from beginning of dorsal to lund-margin of candal fin . . . 



Distance from anns to liind-margin of candal fin 



Lengtli of anterior margin of dorsal fin 



Vertical lieight of dorsal fin 



Distance from tip to tip of caudal flukes 



From these measurements it may be concluded that the dorsal fin has a com- 

 paratively more posterior situation in the foetus tlian in the semi-adult, as its di- 

 stance from the tip of the snout is in the latter only 53, 3 % of the total length 

 against resp. 67, n % and 61, 3 % in the foetuses. The corresponding percentages 

 expressing the distance from the snout to the end of the dorsal fin are in the semi- 

 adult 64,7, and in the foetuses resp. 74,i and 67, . The first and the last of these 

 latter percentages fall within the limits of variation for the same relative measure- 

 ment of the northern Humpback, as recorded by True (20), although the percentage 

 for the semi-adult southern Humpback is just at the lower limit of that of the north- 

 ern. If any conclusion could be drawn from a single measurement like this, it would 



2 /-' 05 12—15 



motlier 



aliot 



oiuthe 



öhot 



rulles off 



2S /--' 05 



8—9 



in the 



middle 



Cum berland 



milesoff Cum- 



of Marc 



h 1905 



Bay. 



berland Bay. 



oö' Cumher- 









land 



Bay. 



8,15 III. 



1,4 5 



III. 



1,23 



ill. 



4,35 111. 



98,5 



cm. 



75,5 



ciii. 



5,2 s m. 



107,5 



cm. 



82,5 



c 111. 



2,56 111. 



45,5 



cm. 



35,r, 



cm. 



0,93 111. 



9 



cm. 



7 



cm. 



— 



68 



cm. 



60,5 



cm. 



— 



58 



cm. 



39,5 



cm. 



— 



7,H 



cm. 



7,5 



cm. 



— 



4,3 



cm. 



2 



cm. 



— 



43 



cm. 



36 



c 111. 



