366 DEEP SEA FISHES. 
From a consideration of evidence on the question of a recent thorough- 
fare through the isthmus between the Caribbean and the Pacific there are 
among the hundred or more genera in the collection sixteen or seventeen 
new ones that may be passed with no comment here, as they have no 
ascertained distribution outside of the Panamic region of the Pacific, and 
besides these there are a dozen others that may also be put away because 
they have not yet been discovered on the Atlantic side of the isthmus. Of 
the remainder the following thirty-eight are known to occur in both the 
Panamic and the Caribbean sections, the latter including the Gulf of Mexico: 
Raia, Centroscyllium, Pontinus, Hoplostethus, Trichiurus, Chiasmodus, 
Lophius, Chaunax, Oncocephalus, Dibranchus, Prionotus, Peristedium, Calli- 
onymus, Lepophidium, Dicrolene, Monomitopus, Bassozetus, Lamonema, 
Phyciculus, Bregmaceros, Macrurus, Monolene, Symphurus, Sternoptyx, 
Argyropelecus, Cyclothone, Chlorophthalmus, Ipnops, Bathypterois, Mycto- 
phum, Stomias, Bathytroctes, Alepocephalus, Halosaurus, Uroconger, Con- 
germurena, Ophichthys, and Cryptopterus ; and the list of those represented 
in the Panamic and in the Atlantic, but not yet found in the Caribbean and 
the Gulf is as follows: Isistius, Trachichthys, Caulolepis, Melamphaés, Care- 
proctus, Paraliparis, Gymnelis, Lycodes, Mixonus, Porogadus, Diplacantho- 
poma, Bassogigas, Merluccius, Antimora, Trachyrhynchus, Maurolicus, 
Chauliodus, Idiacanthus, Notacanthus, Chlopsis, Venefica, Serrivomer, Lab- 
ichthys, Nemichthys, and Myxine. Some of these have ranges so extensive 
as to indicate a ready passage from one ocean to the other by way of 
either the Arctic regions or the Antarctic; for instances Careproctus, Para- 
liparis, Gymnelis and Lycodes range so far to the north that they may pass 
through the Arctic, and others as Raia, Centroscyllium, Merluccius, Anti- 
mora, Macrurus, Cyclothone, Myctophum, Stomias, and Notacanthus have 
distributions indicative of possible migrations through a strait at some time 
crossing the Central American isthmus, and which also show freedom of way 
through both of the polar oceans. The genera taken by this expedition in 
the Panamic region, known also to occur in the Atlantic, and possessed of 
recorded distributions that would somewhat exclusively favor a passage 
through a Panamic strait comprise more than forty per cent of the whole 
number captured, as shown in the following list: Pontinus, Hoplostethus, 
Caulolepis, Trachichthys, Trichiurus, Chiasmodus, Lophius, Chaunax, Onco- 
cephalus, Dibranchus, Peristedium, Callionymus, Lepophidium, Mixonus, 
Dicrolene, Porogadus, Monomitopus, Bassozetus, Diplacanthopoma, Bassogi- 
