CEPHALOPODS. 471 



Fig- 373- Fig. 374. 



Acephals. 



with arteries and veins, and organs of respiration and 

 reproduction.* They are divided into three classes, 

 Cephalopoda or Cephalopods, Gasteropoda or Gastero- 

 pods, and Acephala or Acephals. 



SECTION I. 



THE CLASS OF CEPHALOPODA, OR CEPHALOPODS. 



THE Class of Cephalopoda comprises mollusks whose 

 head is distinctly marked, and furnished with a large and 

 prominent eye on either side, and crowned with longer 

 or shorter fleshy flexible appendages, or arms covered 

 with cups, suckers, or hooks. These arms serve both 

 as organs of locomotion and prehension, and the cups or 

 suckers enable these animals to adhere with the greatest 

 tenacity to whatever body they embrace. They swim 

 with the head backwards, and crawl with the head be- 

 neath and the body above. Surrounded by the arms or 

 fleshy appendages mentioned above is the mouth, armed 

 with two stout horny jaws resembling the beak of a par- 

 rot ; the tongue bristles with horny points ; the oesopha- 

 gus swells into a crop, and then communicates with a 

 gizzard as fleshy as that of a bird, to which succeeds a 

 third membranous and spiral stomach, which receives the 



* Professor J. D. Dana defines Mollusca as follows : "The structure essen- 

 tially a soft, fleshy bag, containing the stomach and viscera, without a radi- 

 ate structure, and without articulations." 



