288 DISCOVERY REPORTS 



little attention except in Azores whales. No differences are apparent in the range and average numbers 

 of mandibular teeth in whales from the three regions (p. 251). Information on parasites is rather 

 extensive geographically, coming from several localities besides the three main ones (p. 252 ff.). 

 Since diatom film has never been observed on whales from tropical and equatorial regions, it is par- 

 ticularly interesting that sperm whales from Scotland in the north and from South Georgia in the 

 south should be parasitized by what appears to be the same skin diatom, a species of Navicida (p. 252). 

 The stalked barnacle Conchoderma auritum is known from sperm whales north and south. C. virgatum, 

 epizoic on a penellid from an Azores sperm whale, is recorded with the same habit from a southern 

 blue whale, and no doubt more attention to this species would record it from the southern sperm 

 whale also. The same applies to the degenerate copepod Penella balaenopterae recorded from a sperm 

 whale in the Azores and from southern blue and fin whales. Of the three species of whale lice so far 

 identified from sperm whales, Cyamus (Neocyamus) physeteris is known only from the North Atlantic, 

 but C. catodontis has been recorded from North Atlantic and North Pacific sperm whales ; and it has 

 been suggested that the third species Paracyamus {Cyamus) boopis, from the South Indian Ocean, 

 may be identical with C. catodontis. Of the internal parasites, the nematode Anisakis physeteris is 

 cosmopolitan in sperm whales. The cestode Priapocephalus grandis is recorded from northern and 

 southern stocks. 



There are a few attributes which might suggest some possibility of segregation. Some further work 

 might be undertaken to see if maxillary teeth do erupt more often in southern than in northern whales 

 (p. 251). Discrepancies at present exist between the sizes at which male sperm whales are considered 

 to reach sexual maturity in different oceans. On present estimates males of the North Atlantic mature 

 at a mean length some 4 to 6 ft. (1-2 to i-8 m.) shorter than North Pacific males and 8 to 10 ft. (2-4 to 

 3-0 m.) shorter than southern males. However, because of size regulations, few of the smaller (im- 

 mature) whales have been available to workers in the North Pacific and the southern seas. Were they 

 available, it is likely that the observed difference between North Pacific and North Atlantic males 

 would vanish, since females of these two stocks mature at about the same size. One may not say 

 whether or not the difference would vanish (though it would probably diminish) when applied to 

 southern males, because there is no precise information on the size at maturity of southern females 

 which might be a guide (p. 266). A last point is the established fact that the sexual seasons of northern 

 and southern female sperm whales both occur in the spring of their respective hemispheres, that is, 

 they are the same in season but in opposite months (p. 270). This is presumably true of males also 



(P- 273)- 



The sperm whale is a species whose 'headquarters... is the tropics' (Matthews, 1938, p. 159), and 



one whose females do not seem to range beyond about 40 N. and S., that is, not so far as the 



limits of the continents, except in regard to the Cape of Good Hope. One would therefore expect 



that any differences between the stocks would be more likely to be between whales of the oceans 



east and west, rather than between those of the north and south. Yet there is at present no evidence, 



apart from the very doubtful matter of a size difference in males at sexual maturity, to suggest that 



sperm whales of the North Pacific differ significantly from those of the North Atlantic. If there is 



no segregation, then continuity is presumably maintained by those males which in summer move 



beyond the continental limits into the circumpolar ocean. Few sperm whales have yet been marked in 



the Antarctic, and there is no reliable evidence of east-west interchange in Maury's solitary remarks 



that he had ' often met sperm whales off the Cape of Good Hope and off Cape Horn, making their 



passage from sea to sea ' and that he knew of a sperm whale killed on the Atlantic seaboard * of the 



* Maury mentions only 'the coast of the United States', but the state of the Union at that date (1852) shows that the 

 Atlantic seaboard was intended. 



