THE PAST AND PRESENT OF CUTTLE-FISHES. 755 



arms of the cuttle-fish head as the representatives of the missing 

 velum. But, as the latter organ always exists on the dorsal or upper 

 side of the mouth, and as the arms are placed originally behind and 

 under the cuttle-fish mouth, the correspondence of arms and velum 

 has not been accepted by zoologists. On the other side stands out the 

 opinion of Huxley, who regards the " arms " of the cuttle-fish head as 

 more truly corresponding with the " foot " of the mussel, snail, and 

 other mollusks. 



The margins of the foot, in this view of matters, have been pro- 

 longed in the young cuttle-fish to form eight, ten, or more arms, and 

 the front and sides of the foot, having overgrown the mouth, are 

 united in front, so that the mouth appears to be placed in the center 

 of the foot, instead of in front and above it, as in other mollusks. 

 So, also, most naturalists maintain, and with every appearance of cor- 

 rectness, that the characteristic " funnel " of the cuttle-fishes to be 

 hereafter referred to is an organ formed by two side-processes of the 

 foot, named epipodia. Adopting the view thus sanctioned by compe- 

 tent authority, we may trace in a cuttle-fish the highly modified form 

 of a snail or whelk, and the still more modified form of the mussel 

 tribes. The foot, instead of growing backward and downward as in 

 the snail, and thus forming a broad walking disk, comes to grow over 

 the mouth in front. So that, placing a cuttle-fish in structural com- 

 parison with a whelk or mussel, we should have to set it head down- 

 ward, when the foot (or arms) would be lowest, and the great bulk of 

 the body, with the heart uppermost, would be situated, as in the snail, 

 above the foot. 



The group of the cuttle-fishes may be said to divide itself in the 

 most natural fashion into two main divisions. The first of these 

 groups includes all living cuttle-fishes save one the pearly nautilus. 

 This first division is that of the Dibranchiates, or two-gilled cuttle- 

 fishes. The familiar octopus (Fig. 1), the loligos or squids, the sepias, 

 and the argonauts or paper nautili, are among the best known of its 

 representatives. The second group is represented by a single living 

 cuttle-fish, the pearly nautilus (Nautilus JPompiUus), just mentioned, 

 and by many fossil and extinct forms. 



One of the most remarkable traits of cuttle-fish existence is the 

 curious play of " shot " colors which takes place in their integument. 

 I have seen a loligo, or squid, stranded on the sea-beach make glorious 

 its dying agonies by a play of colors of the most astounding descrip- 

 tion. The natural purplish tint of the body was now and again deep- 

 ened to well-nigh a dark blue ; the slightest touch served to develop 

 a patch of angry pink ; and continually over the whole surface of the 

 body the hues and tints, ranging from dark purple to light red, suc- 

 ceeded each other in rapid array. 



The assimilation of an animal's color to the surfaces on which it 

 rests forms a notable circumstance of zoology, which has been denom- 



