1888.] POISON-ORGANS OF TRACH1NUS. 361 



opercular spine as "an offensive weapon/' while Saville Kent (15) 

 makes similar statements to those of Giinther and Day. 



Turning now to observers in other countries, I find that Cuvier 

 (6, 7, & 8) and Bleeker (2; quoted by Dr. Giinther, 13) not 

 only deny the existence of a gland, but even state that it is a mis- 

 take to suppose that the Weevers are poisonous at all. Cuvier, 

 moreover, mentions the dorsal spines only. And as recently as 

 1886, Tybring (19) has made the following statement: "In the 

 Norwegian waters there are no poisonous fishes, but it is well known 

 that the sting-bull [a local name for the Greater Weever, see Day, 

 9], may be dangerous if one happens to run the pointed dorsal fin 

 into the finger, or any other part of the body." 



Canestrini (4) gives a brief reference to Byerley's paper, and 

 acknowledges his conclusions. 



In Wiedersheim's ' Lehrbuch d. vergl. Anatornie '(20) the following 

 passage occurs in the chapter on the integument (p. 20) : " Weiter 

 gehort dahin die unter der Stacheln der Riickenflosse von Trachinus 

 liegende Giftdriise. Sie ruht jederseits auf dem Grund vom sack- 

 artigen Haut-Einstiilpungeri, wahrend ihre Ausfiihrunsgange im 

 Bereich der Stacheln liegen." (See also 21.) I am unable to state on 

 whose authority this statement is made, as Professor Wiedersheim can- 

 not at present lay his hands on the paper from which the passage was 

 abstracted. But it will be noticed that no mention is made of the 

 opercular poison-organ ; and that the description of the glands of the 

 dorsal spines differs considerably from my own observations. 



Before sending in the present paper for publication, a reference 

 was given me by Professor Hubrecht to a work by Gressiu (14), 

 and I much regret that I have been unable to obtain a copy, especi- 

 ally as from its title it is probably an important contribution to the 

 subject. But as apparently this work is not known to most English 

 ichthyologists, I have been advised to publish my own observations 

 independently. 



STRUCTURE OF THE POISON-APPARATUS. 



Opercular Organs. The form of the opercular spine and its rela- 

 tion to the bony operculum are shown in the accompanying drawing 

 (fig. 1, p. 362). A deep groove (gr) runs along both upper and under 

 surfaces right to the apex ; and where the base of the spine joins the 

 operculum the grooves are continued forwards for a short distance 

 into small conical cavities (z), entirely surrounded by bone. Fig. 2 

 represents the third dorsal spine, which is slightly stouter than the 

 others ; the grooves here also extend from base to apex. 



Both figs. 1 and 2 are taken from T. draco ', the other figures 

 (Plate XVII.) refer to T. vipera. I find there is no important 

 difference between the two species as regards the structure of the 

 apparatus, and have chosen the smaller species for histological exami- 

 nation, as it requires less decalcification and is more convenient for 

 preparation. 



1 I am indebted to Mr. J. J. Neale of Cardiff for a fresh specimen of this fish. 



