568 DEEP SEA FISHES. 
south latitude of 55° or more, in all oceans, in fact, this genus can be relied 
on to establish very little concerning an eastward strait from the Panamic 
or another from the Mediterranean. The species now known from the 
Caribbean and those from the Panamic region are not very closely allied. 
Centroscyllium : —Is taken in the Panamic region, in the north Atlantic 
to Greenland, near the Falkland Islands, in the Mediterranean Sea, the 
Arabian Gulf, and the Bay of Bengal, but has little bearing on early 
connections across Panama and Suez because of the close agreement of 
the species throughout the entire range. 
Isistius : — Ranging from the Panamic to Alaska, in 55° north, and to the 
middle Pacific, found in the Atlantic at Rio de Janeiro, in the Gulf of Guinea, 
and in the Indian Ocean from Madagascar to Australia, this shark is one 
of the most likely to pass from ocean to ocean at the southward of either 
America or Africa. 
Pontinus: —The present record from the Panamic, from the Gulf of 
Mexico to Cape Hatteras, from the Mediterranean and from off the north- 
west coasts of Africa, places this genus strongly in favor of recent migrations 
through a Panamic strait. 
Hoplostethus : — A distribution in the Panamic region, through the 
Caribbean and the Gulf of Mexico to New York, from Madeira and the 
northwestern coasts of Africa to the Mediterranean, in the Bay of Bengal, 
and in the Sea of Japan, makes Hoplostethus at once favorable to a migra- 
tion westward from the Caribbean and to that advocated by Alcock between 
the Mediterranean and the Indian Ocean. 
Trachichthys : —Known from the Panamic region, from Chili, from 
northwest Africa to the Mediterranean, from the Bay of Bengal to Japan, 
Australia and New Zealand, this genus must be regarded as a likely one 
to range southward of the great continents. 
Cuulolepis : — The position of the three localities from which this genus 
has been recorded, off New York, off Lower California, and off Panama, 
together with the very close relationship existing between the species of 
the Atlantic and that of the Pacific, renders Caulolepis one of the best for 
the present to cite in support of a recent thoroughfare across the isthmus 
of Panama. 
Melamphats : — From the Panamic to Puget Sound, the western Central 
Pacific, off the eastern coasts of the United States and of South America, 
off the northwestern coasts of Africa, from the Bay of Bengal and from the 
