16 



Guide to the Invertelrata. 



Squids. open water of the warmer seas, such as the Mediterranean, the 

 GALLERY Indian, and China seas. One species, A. hians, Sol., occurs fossil 

 in the Pliocene beds of Piedmont. 



In the Octopodidae (Fig. 17) the dorsal arms are not expanded as 

 in Argonauta, but are more elongated, and united by a web at the 

 base. The shell is quite rudimentary, but is represented by two 

 short stylets enclosed in the mantle. The body is oval, without 

 fins; the skin is warty and richly covered with pigment-cells; 

 the arms, which are of unequal length, are each provided with 



Fig. 36. — Cheiroteuthis Veranyi, D'Orb. Atlantic. (Reduced.) a, the 

 animal ; b, a single booklet, enlarged ; c, the internal shell or pen. 



two rows of suckers (Fig. 21), there being as many as 120 pairs 

 on each arm. The eyes are of moderate size, but the beak is very 

 strong and recurved (Fig. 22). 



There are six genera living at the present day : of these Octopus 

 is the most cosmopolitan, being found along all the temperate 

 and tropical coasts of the globe. Forty-six living species have 

 been described. A single example occurs fossil in the Cretaceous 

 beds of the Lebanon, named Palceoctopus ( Calais) Newholdi, which 

 has triangular fins on the sides of its body. 



(h) Decapoda. — From the eight-armed division of the Dibranchiata 

 we pass to the ten-armed "Squids" and ' * Calamaries " (called 



