GEPHALOPODS. 



75 



Class III. — Cephalopoda [Cuttle-fish, Squid). 



General Characters of Cephalopods.- — In these mollusks 

 (Fig. 88) the head in front of the eyes is divided into arms 

 usually provided with suckers; the eyes are large, and nearly 

 as perfect as in fishes. The brain is large, and with the 

 other important nervous ganglia lodged in the head and 

 protected by pieces of cartilage. The mouth-cavity (phar- 

 ynx) is armed with two teeth like a par- 

 rot's beak, besides a lingual ribbon (Fig. 

 89). The body is supported by a horny 

 "pen" (Fig. 90). 



The Cephalopods are divided into two 

 orders. The first order ( Tetrdbrcmcliiata) 

 have four gills within the mantle; such 

 is the Nautilus (Fig. 91, N. ijomjnlius). 

 The -,^,-|j, cd order, Dihranchiata, is so 

 callec-inils Ca having but two gills. The 

 Octopods (Fig. 92) have eight arms, and 

 the squid or cuttle-fish have ten. The 

 largest known squid is Architeidhis 

 princeps (Fig. 93); the body of the 

 specimen here figured measured nine 



Fig. 89— Part of lingual ribbon of 

 Loligo Hartingii; mucli en- 

 larged. 



Fio. 90.— Pen of 

 Loligo pallida, 

 dorsal side ; nat- 

 ural size. 



ind a half feet from the tip of the tail to the base of the 

 arms, and was seven feet in circumference. The longer 

 arms were thirty feet in length. Ordinary squids are 

 about a foot long. 



The paper nautilus {Argo7iauta argo) has a beautiful 



