DR. GUNTHER ON THE FISHES OF CENTRAL AMERICA. 439 
mens were preserved, as to be impassable to the fluid of injection. A great part of the 
lateral-line system consists of open canals; however, on some parts of the body, these 
canals are entirely covered by the skin: thus, for instance, the open lateral line ceases 
apparently in the suprascapular region, being continued again in the parietal region. 
We could not discover any trace of an opening by which the open canal leads to below 
the skin; yet we could distinctly trace the existence of the continuation of the canal 
by a depressed line, so that it is quite evident that such openings do exist, although 
they may be passable only in fresh specimens. Thus, likewise, the existence of openings 
in the bags, as I believe to have found in the first specimen dissected, may be proved by 
examination of fresh examples. 
The sacs are without an external muscular layer. and situated immediately below the 
loose thick skin which envelopes their spines to their extremity; the ejection of the 
poison into a living animal, therefore, can only be effected by the pressure to which the 
sac is subjected the moment the spine enters another body. 
Nobody will suppose that a complicated apparatus like the one described can be 
intended for conveying an innocuous substance; and therefore I have not hesitated to 
designate it as poisonous; and, Capt. Dow informs me in a letter lately received, “ the 
natives of Panama seemed quite familiar with the existence of the spines and of the 
emission from them of a poison which, when introduced into a wound, caused fever, an 
effect somewhat similar to that produced by the sting of a Scorpion; but in no case was 
a wound caused by one of them known to result seriously. ‘The slightest pressure of 
the finger at the base of the spine caused the poison to jet a foot or more from the 
opening of the spine.” The greatest importance must be attached to this fact, inas- 
much as it assists us in our inquiries into the nature of the functions of the muciferous 
system, the idea of its being a secretory organ having lately been superseded by the 
notion that it serves merely as a stratum for the distribution of peripheric nerves. 
Also the objection that the Sting-Rays and many Siluroid fishes are not poisonous, 
because they have no poison-organ, cannot be maintained, although the organs conveying 
their poison are neither so well adapted for this purpose nor in such a perfect connexion 
with the secretory mucous system as in Thalassophryne. 
The poison-organ serves merely as a weapon of defence. All the Batrachoids with 
obtuse teeth on the palate and in the lower jaw feed on Mollusca and Crustaceans. 
95. ANTENNARIUS LEOPARDINUS. (Plate LXIX. fig. 3.) 
Giinth. Proc. Zool. Soc. 1864, p. 151. 
DreSl3 seAC ee awl, 
Skin very rough, covered with minute spines; anterior dorsal spine (tentacle) not 
longer than the second, terminating in a small, flat disk; the third is separate from the 
_ soft dorsal. .Brownish grey, marbled with rose-colour, and with brown dots on the 
