272 



DISCOVERY REPORTS 



from ' Other gear ', and two others at which there was some doubt as to the depth logged, have been 

 excluded from the former: 



Psammobatis microps (Gunther) was not taken by the expedition's ships, but it is known from the 

 mouth of the Plate and may occasionally range as far south as the northern part of the area we sur- 

 veyed. 



CHIMAERIDAE 



Callorhynclms callorhynchiis (Linnaeus). Our records of this species show that it was very definitely 

 confined to the warmer inshore waters in our area. Most of our specimens were taken in the northern 

 region, in spring. Single records in the intermediate region (autumn) and in the southern region 

 (late summer, coincident with maximum temperatures for the year) suggest the possibility of a 

 N-» S^ N migration along the coast. The distribution is shown in Fig. 17, and the depth relations 

 in Fig. 18.. Callorhynchiis occurred in the trawl only, none being taken in 'Other gear'. 



Norman (1937, pp. 35-6) has shown that Carman's (1904, 191 1) distinctions between two 'species' 

 of Callorhynchiis on either side of South America cannot be maintained. C. srnythii Bennett, 1839 

 should be regarded as a synonym of C. callorhynchus (Linnaeus), 1758. Norman further stated that 

 ' It is probable that the examination of an adequate series of specimens would show that the nominal 

 species capensis, from South Africa and milu, from Australia, Tasmania and New Zealand, are nothing 

 more than varieties of C. callorhynchus'. Careful study of Carman's keys inclines one to agree. All the 

 external characters, such as the relative extent of various fins and so forth, given as diagnostic by 

 Carman, show complete overlapping. Most of them were exhibited within the limits of our own 

 series of C. callorhynchus. They would be better described as agnostic characters. One is left with the 

 modifications of the palatine teeth as the only character on which a distinction can be based, and 

 Carman himself (191 1, p. 97) remarks on the danger of such a practice on account of the extent to 

 which the teeth may change with age and use. 



Barnard (1925, p. 96) maintained that Carman's recognition of C. capensis Dumeril as distinct from 

 C. callorhynchus was correct 'on the form of the dental plates'. He examined many specimens, but 

 does not say how many or of what size, though from two maximal measurements given it is certain 

 that he saw at least two large specimens. 



Is the form of the tritors of the palatine lamellae a good specific character? They are essentially 

 the same m the young of all these 'species', and no author has yet defined the stage at which the 

 differentiation becomes apparent. Moreover, the fossil C. hectori Newton, 1876 is said by Carman to 

 agree with C. capensis in respect of this character. This fossil was found in M^hat are probably cretaceous 

 rocks m New Zealand. One can recall teleosts in which teeth regarded (by some) as diagnostic in the 

 adults are absent m the young and 'occasionally absent' in large specimens. 



