92 Mil. J. T. CUNNINGHAM ON MARINE FISHES [Jan. 18, 



Species found also at the West Indies. 



Murcena sanctve helence (Ber- 

 mudas). 

 Murcena moringa. 

 Holocentrum longipinne. 

 Epinephehos aseensionis. 

 Priacanthus cruentatus. 

 Sargus capensis (Bermudas). 



Caranx dentex (Bermudas). 

 Scomber colias. 

 Thynnus albacora. 

 Thyr sites prometheus (Ber- 

 mudas). 

 Platophrys poclas (Cuba ?). 

 Balistes buniva. 



According to E. A. Smith in his paper on the Marine Mollusca 

 of St. Helena, P. Z. S. 1890, the molluscan fauna of the island 

 resembles that of the West Indies, fifty per cent, of the specimens 

 from St. Helena being common to the two localities. The 

 similarity shown by my small collection of fishes is not nearly 

 so great, the proportion of West Indian species, including those 

 found at the Bermudas, being only 11 out of 33, and if we 

 exclude the Bermudas and omit Platophrys podas, which is doubt- 

 ful, we have only 6 out of 33. A few of the species occur both 

 in the Mediterranean and at the Cape, namely Lichia glauca, 

 Scomber colias, Thynnus alalonga, and probably Caranx dentex, 

 which certainly occurs at Port Natal (Durban). The few remain- 

 ing species show no special affinity of the St. Helena fauna with 

 either the Mediterranean or the Cape. On the other hand, avast 

 number of Mediterranean and South African species do not occur 

 at St. Helena, these being northern and southern temperate 

 forms which are probably excluded by temperature. In fact, if 

 we omit the oceanic forms of wide distribution, such as the species 

 of Thynnus, the shallow-water fishes of St. Helena are few in 

 number of species ; and the fact that such a large proportion 

 are peculiar to the island, shows how isolated the fish-fauna is, in 

 spite of the fact that the eggs and larvae are pelagic. The 

 fauna belongs to the tropical Atlantic, but comparatively few of 

 the species of this fauna have established themselves on this small 

 and isolated area in mid-ocean, and the arrival of new indi- 

 viduals from other regions must be a. rare occurrence. 



With regard to the species common to the Atlantic and Pacific, 

 it is an interesting question whether there is any interchange of 

 individuals between the two oceans or whether the populations of 

 the same species have been isolated since the oceans were sepa- 

 rated by the elevation of the Isthmus of Panama. If there is any 

 interchange it must take place round the Cape of Good Hope, as 

 warm-water fishes are not likely to travel round the cold shores 

 of Cape Horn, and at the African cape the cold Benguela current 

 from the Antarctic offers an obstacle. Scomber colias is common 

 at the Cape, but not known in the Indian Ocean. Thynnus 

 alalonga occurs in South African wa/ters, but the other species of 

 Thynnus are not recorded. T. albacora occurs at Muscat, and 

 both this species and Gymnosarda alleterata are taken on the 

 coasts of India and the East Indies, but not at the Cape. 



