VENOMS IN THE ANIMAL SEBIES 809 



and furnished with hooked denticulations, which cause them to 

 remain in the wound, in which they break off. Near their extremity 

 there opens a small canal, which communicates with the culs-de-sac 

 situated at the base of the spiny rays, which produce a venomous 

 secretion. The dorsal spine has only a single cul-de-sac, while the 

 pectoral spines have two. 



The contraction of the local muscles, by compressing these culs- 

 de-sac, can cause the venom to make its way into the canal of the 

 spine, but the fluid does not spurt forth in a jet as in the case of 

 Synanceia. The poison-apparatus is therefore passively defensive in 

 character. Plotosus is capable of wounding only when the hand 

 or foot is placed on its dorsal or pectoral spines. 



Fishermen who are stung immediately feel an excruciating pain, 

 which is soon accompanied by fever, and lasts for several days. 

 Accidents caused by this fish are of fairly common occurrence in 

 Eeunion. 



2. — Mureenidse. 



Of the fishes belonging to this family, the species of the genus 

 Murcena alone concern us. They have an elongated body, without 

 pectoral fins, and a naked skin, covered with a thick layer of viscid 

 slime, as in the case of the eels. Their dentition is powerful, formed 

 of long, recurved fangs, arranged in one or more rows. These fishes 

 may attain a large size, exceeding 2 metres in length. More 

 than one hundred species are known, all of which live in tropical or 

 subtropical seas. Murcena helena is common in the Mediterranean 

 in the vicinity of Nice and Toulon ; M. moringa (fig. 120) is found 

 in the Tropical Atlantic. 



The species of Murmna live in deep water, and feed upon fishes or 

 crustaceans. In hot countries they frequently venture into fresh 

 water. Their skins are adorned with brightly coloured markings, 

 which vary very greatly according to the species. 



The poison-apparatus in Murcena consists of a pouch situated 



