36G 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 

 amonc 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 j-et 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, Oncocejihalus, Dibranchus, Prionotus, Peristedium, Calli- 

 onymus, Lepophidium, Dicrolene, Monomitopus, Bassozetus, La3monema, 

 Phyciculus, Bregmaceros, Macrurus, Monolene, Symphurus, Sternoptyx, 

 Argyropelecus, Cyclothone, Chlorophthalmus, Ipnops, Bathypterois, Mycto- 

 plium, Stomias, Bathytroctes, Alepocephalus, Halosaurus, Uroconger, Con- 

 germuraina, Ophichthys, and Crjptopterus ; 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, Melamphacs, 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- 



