DR. GUNTHER ON THE FISHES OF CENTRAL AJVIERICA. 439 



mens were preserved, as to be impassable to the fluid of injection. A great part of the 

 lateral-line system consists of oij)en 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 system, the idea of its being a secretory organ having lately been superseded by the 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 MoUusca and Crustaceans. 



95. Antennabius leopabdinus. (Plate LXIX. fig. 3.) 

 Gunth. Pioc. Zool. Soc. 186-t, p. 151. 



D. 3|13. A. 7. P. 11. 

 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 witli rose-colour, and with brown dots on the 



