RETREAT 373 



five clouds of ink in the clear water. The appearance in the 

 neighbourhood of a small shark or other kind of voracious fish was 

 the cause of this sudden agitation, and the cuttle-fishes, after 

 squirting out a cloud of ink to * throw dust in the eyes ' of their 

 enemy, had, by violent contractions of their mantle, made off." 



Certain kinds of Land -Snails have been described which often 

 succeed in escaping their enemies by the same kind of device as 

 that described for Lizards. This is the case, for instance, with a 

 number of small forms of the kind (species of Helicarion) inhabit- 

 ing the Philippines. These crawl rapidly upon trees by means of a 

 long narrow foot, of which the hinder part is very conspicuous and 

 bears a projecting horn-like process. If such a snail, when crawl- 

 ing, is seized from behind, this tail-like part of the foot is jerked 

 convulsively up and down till it becomes detached, when its owner 

 promptly drops to the ground or conceals itself among adjacent 

 leaves. 



A common British Land-Snail ( Vitrina pellucida) uses the 

 tail-like hinder part of the foot as a springing organ, by which it 

 can throw itself to the ground if alarmed when crawling along 

 in an exposed situation. Some Sea- Snails possess jumping powers 

 of no mean order (e.g. species of Strombus and its allies) which 

 must often be of use in helping them to retreat from enemies. 

 Even some of the bivalve molluscs are endowed with similar 

 powers, as is notably the case in the Common Cockle (Cardium 

 edule], and here again rapid and sudden retreat from foes is no 

 doubt one of the ends served. 



Some of the Social Insects, especially Ants, wage warfare very 

 scientifically, and their retreats are carried out in good order, regu- 

 lated by tactical principles. There are also insects with special 

 powers of fighting in retreat An example is the Bombardier 

 Beetle (Brachinus crepitans], in which the hinder part of the intes- 

 tine is provided with glands which secrete a volatile fluid possessed 

 of noxious properties. When one of these creatures is pursued by 

 a large carnivorous beetle it ejects small portions of the fluid, 

 which immediately vaporizes, producing what looks like a tiny puff 

 of smoke. At the same time a sharp report is heard, resulting 

 from the sudden ejection, and the arrangement is one calculated 

 to discomfit an enemy. 



Spiders combine death-feigning with retreat, falling from their 

 webs when attacked as if the victims of sudden dissolution. They 



