DB. r. LBUTHNER ON THE ODONTOLABINI. 483 



easily accounted for, as these were already islands ', at least in part, at the same period. 

 Thus these small species, which are far inferior to their continental allies in size, must 

 he regarded as antiquated forms. 



In like manner the original home of the species of OdontolaUs must he sought for in 

 Further India. 



0. carmatus, which occurs in Ceylon and on the east coast of India, is certainly of 

 Malayan origin. It is difficult to determine whether it has migrated from the south by 

 some previous land-communication or from the north ; but Wallace has shown that 

 several of the mammals, birds, and reptiles of Ceylon are likewise of Malayan origin ^. 

 The species which occur on the other islands show no exceptional distribution ; for 

 although many of them are peculiar species, yet they are closely connected with others 

 found either on the continent or on the large adjacent islands. But although the 

 Philippines are nearer to the Chinese coast, their species show a greater affinity to 

 those of the Svmda Islands than to those of Formosa. 



Lastly, the two species of the genus Heterochthes are confined to Siam and to the 

 Andaman Islands respectively. 



As the accompanying Table will show, species occurring in the same locality are 

 generally so dissimilar that their interbreeding is quite impossible, and it is not 

 unlikely that they may arrive at maturity at different seasons, in which case they would 

 be still less likely to interfere with each other. 



For example, the following species are met with in the peninsula of Malacca : — 

 \. Neolucanu,s cingulatus. Parry; 2. OdontolaUs striatiis, Deyr. ; 3. 0. mratus, Hope; 

 4. 0. wollastoni. Parry; 5. 0. gazella, Fabr. ; 6. 0. latijjennis, Hope. 



In Sumatra we find : — 1. N. lanshergii, Leuthn. ; 2. 0. castelnaudi. Parry ; 3. 0. soni- 

 meri, Parry ; 4. 0. latipennis, Hope ; 5. 0. wollastoni. Parry ; 6. 0. ludeMngi, Vollenh. ; 

 7. 0. lacordairii, Vollenh. ; 8. 0. gazella, Fabr. ; 9. 0. dalmani, Hope. 



But when closely allied species occur in the same locality, intermediate forms (or 

 hybrids?) are of ii'equent occurrence, which circumstance renders the species difficult 

 to separate (comp. pp. 412-414). 



A comparison of the number of species will give the clearest idea of the important 

 part migration and isolation have played in their differentiation, 



' Comp. K. Martin : " Die wiohtigsten Daten unserer geologischen Keuntniss vom Niederlandisoh Indischen 

 Archipel " (Tijdschrif t van het KoninkHjk Instituut voor de Taal-, Land- en Volkenkunde vau Nederlandsch 

 Indie, 1883). 



^ Wallace, Geographical Distribution of Animals, vol. i. p. 327. 



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