318 DISCOVERY REPORTS 



The foregoing papers were based on fishes from the Atlantic and Antarctic areas, but quite recently 

 Abe (1952) and Hubbs, Mead and Wilimovsky (1953) described specimens from the north-east and 

 north-west Pacific. The latter workers also made a close study of the literature and concluded that 

 there is no good evidence for recognizing more than one species, pharao, of the genus Anotopterus. 



The study of the type of Eugnathosaurus vorax and of the two specimens mentioned earlier, together 

 with a specimen from Madeira and published papers, has led me, independently of these ichthyologists, 

 to much the same conclusion. But there is some indication that this one species may be differentiated into 

 a northern and southern form ; further material may even show that these ' forms ' might better be re- 

 garded as separate species. However this may be, my present intention is to bring forward new data 

 on Anotopterus and then to point out the differences between fishes from the northern and southern 

 seas. Much of the ground I had intended to cover regarding the status of the species of Anotopterus 

 has already been thoroughly dealt with by Hubbs et al. (1953). 



Comparison of the type specimen of Eugnathosaurus vorax Regan (borrowed from the Royal Scottish 

 Museum) with the large Antarctic specimen taken by the whale-catcher has shown them to be closely 

 similar. The measurements in millimetres are given below, those for the type coming first, followed in 

 parentheses by those of the complete fish. 



Length of head 150 (147); length of snout 89 (89); horizontal diameter of bony orbit 15*5 (i4*5); 

 width of bony interorbital 8-o (8-o); postorbital length of head 46 (46); length of mandible in (108); 

 length of premaxillae 90 (89); length of largest palatine tooth 9-5 (10*5). 



Dentition. The type specimen has no teeth on the first fifth of the length of the left mandible, then 

 come twelve small, pointed and more or less upright teeth, then seven larger teeth inclined backwards 

 and then two squat teeth, shaped rather like a rose thorn. Between the second to fifth mandibular teeth 

 three smaller ones are inserted. In the complete Antarctic specimen, the arrangement of teeth on the 

 left mandible is very similar: there is a short, foremost toothless part, followed by seventeen small, 

 pointed teeth (the first seven of which are inclined forward), then by seven large retrorse teeth and 

 finally by two small thorn-like teeth. 



The palatine dentition of the type is well-illustrated in fig. 1 (p. 234) of Regan's (1913) paper. In 

 addition to the teeth shown in this figure, I have found indications of others. There are certainly the 

 remains of a tooth base between the second and third teeth of the right palatine and there are indica- 

 tions of another base in front of the first tooth. On the left palatine there is a tooth base between the 

 second and third teeth ; this base is a clear-cut oval with a brownish centre, perhaps an indication of a 

 resorbed tooth. Thus the type had thirteen functional teeth, two of these having been detached at some 

 time. 



The palatine dentition of the complete individual is shown in Text-fig. 6b. As well as the eleven 

 upright, functional teeth, there are a number of recumbent teeth lying in the dental integument and 

 one obliquely set tooth. The latter is quite hard and is evidently moving upwards into position. The 

 recumbent teeth can be divided into two types: (1) moderately ossified teeth (shown in the figure by 

 cross hatching), and (2) soft teeth (shown dotted). On the right palatine it will be seen that the last 

 two teeth have soft replacement teeth, while on the left palatine two of the moderately ossified re- 

 cumbent teeth, soon to become functional, are closely associated with what must also be replacement 

 teeth. The tooth pattern suggests that at any time there may be from 11 to 14 palatine teeth 

 in use. 



Presumably tooth succession goes on all the time as in Alepisaurus. It was of such fishes that Owen 

 (1840-5) wrote: ' . . .the succession of teeth is uninterrupted, the pulps of the new teeth are developed 

 in most of the species in the soft gum or integument covering the dentigerous margins of the bones, 

 and the calcification of the pulp is completed as it lies recumbent and buried loosely in the substance 



