302 CEPHALOPODA. 



the ground over which they pass. When in deep 

 water their general shade is brownish purple; but 

 when placed on land or in shallow water, this dark 

 tint changes to one of yellowish green. The colour, 

 examined more generally, is a French grey, with 

 numerous minute spots of bright yellow. The former 

 of these varies in intensity, the latter entirely disap- 

 pears and appears again by turns. These changes 

 are effected in such a manner, that clouds varying 

 in tint between a hyacinth-red and a chestnut-brown 

 are continually passing over the body. 



" I was much amused by the various arts to escape 

 detection used by one individual, which seemed 

 fully aware that I w r as watching it. Kemaining for 

 a time motionless, it would then stealthily advance 

 for an inch or two, like a cat after a mouse, some- 

 times changing its colour ; it thus proceeded till 

 having gained a deeper part, it darted away, leaving 

 a dusky train of ink to hide the hole into which it 

 had crawled." DARWIN, Voyage of the ' Beagle! 



The Calamaries (Loligo}. In the Octopus above 

 described the arms or tentacles are only eight in 

 number, and all nearly of equal dimensions ; but in 

 the Calamaries their number is increased to ten, the 

 additional pair being lengthened into slender cables, 

 at the end of which suckers are grouped together 

 upon flat disks, and thus serve the purpose of 

 anchors whereby the animal attaches itself to the 

 rocks, and rides securely in a tempestuous sea. 

 The general form of the body is comparatively 

 slender, and towards the hinder extremity is pro- 

 vided with a pair of broad triangular fins, wherewith 

 it is enabled to shoot through the water like an 

 arrow. Imbedded in the fleshy substance of the 

 back is a long transparent plate of horn, which in 

 shape bears some resemblance to a pen ; it is to the 

 presence of this curious support that these animals 

 are indebted for their name (Calamus, a pen) ; they 

 are likewise called " pen-fishes." 



The Squids (Loligo piscatorum), or as they are 



