VENOMS IN THE ANIMAL SERIES 309 
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. T'he 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 
Réunion. 
2.—Mureenide. 
Of the fishes belonging to this family, the species of the genus 
Murena 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. Murena 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 Muræna 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 Muræna consists of a pouch situated 
