400 DR. GUNTHER ON THE FISHES OF CENTRAL AMERICA. 
geology will furnish us with the proof of the former partial submergence of a part of 
Central America, as it has done with respect to the northern part of Scandinavia. We 
should then be able to speak with more confidence of the permanence, or rather endu- 
rance, of the characters of a specific type, and arrive at a somewhat more definite idea 
of the age of species which must have existed before those geological changes were 
completed’. 
Sir CuarLes Lye. has directed my attention to collateral evidence from other classes 
of the animal kingdom, by which the partial identity of the faunas of the two coasts is 
shown, although not in an equally conclusive manner. The majority of malacologists 
appear to have presumed @ priori their distinctness, and consequently described Pacific 
shells generally as distinct from Atlantic species. However, Dr. M6rcu, in a paper in 
which he describes or enumerates about 360 Panama species, makes the following 
remarks (Pfeiff. Malakozool. Blatt. 1859, p. 107) :— 
«The tropical [molluscan] faunze may be classed in two principal divisions, the Indian 
and the Atlantic. To the latter belong, 1, the Guinean (Senegalian); 2, the Antillian ; 
and 8, the Panaman, which, although belonging to the Pacific, appears to be most 
analogous to the Guinean. A great number of species, especially of Bivalves, have 
been regarded as identical with those from the eastern (Brazilian) shore. I believe I 
can prove that they are different. Certain irregular mollusks cannot be separated 
diagnostically ; but I can recognize them by their general habit. It is at all events a 
fact that no species stamped with definite characters (wohlausgeprigt) is identical on 
both sides of the isthmus. The Panama species may be divided into:—l, those 
analogous to West-Indian ; 2, those analogous to species from Guinea and Senegal ; 
3, those very remotely analogous to East-Indian species.” 
 T may on this occasion recur to a remark made by me in Proc. Zool. Soc. 1858, p. 381, with regard to the 
sea-snakes observed in the Bay of Panama by M. Sallé, Capt. Dow, and Mr. Salvin. There is now not the least 
doubt that the snakes seen were Pelamys bicolor, and that they are, moreover, very common there. I find that 
Dr. Seemann (Voy. ‘ Herald,’ i. p. 265) already mentions them. But I am much inelined to think that this 
most common Indian species has migrated eastwards, and that its arriyal on the West-American coast is of 
yery recent date. Dampier and the other bucaniers who have left us records of their adventures, and who 
passed weeks and months in the Bay of Panama, could not have failed to observe them, and to mention them 
in their notes, just as they did on other occasions. It is also probable that these snakes would have spread 
into the Atlantic Ocean, had they been so numerous on the Pacific side at the time when a communication 
existed between the two oceans. 
Whilst this paper was passing through the press, I found two notices of the existence of water-snakes 
on the western coasts of South America, in seas considerably more southwards than the Bay of Panama. The 
notes are in Capt. Sharp’s Voyage in ‘* The History of the Bucaniers of America.” London, 1699, 8yo, yol. ii. 
p. 50; “As we sailed” [near Cape St. Francisco, which is nearly under the equator] “we saw multitudes of 
Grampusses every day; as also Water-snakes of divers colours.’ And p. 72, when sailing in lat. 19°S., the 
author mentions “ A huge shoal of fish, two or three Water-snakes, and several Seals.” I find in another part 
of the same work a note which I believe to be the first description of Vapirus bairdi. The part has a separate 
title-page, “A Journal of a Voyage made into the South Sea by the Bucaniers or Freebooters of America from 
the year 1684 to 1689. Written by the Sieur Raveneau de Lussan.” Lond. 1698, 8yo. The Indian name of 
the Tapir is given as Manipourye, page 16, 
