584 BIOLOGY. 



partly by their fleshy body, and in part by their perfect 

 organs of vision. 



The body is often as large as the trunk of a man ; the 

 head being separated from it by means of a neck, has in 

 its interior a kind of cartilaginous brain-case or skull, 

 with externally a pair of jaws resembling a Bird's beak, 

 and with eyes tolerably similar to those of Fishes. Audi- 

 tory organs are also present, which consist of a tympanic 

 cavity inclosing an otolithe or ear-ossicle ; nostrils are 

 wanting. The so-called arms are perfect organs of locomo- 

 tion, as also useful for seizing the prey, being provided for 

 this purpose with sucking cups, which adhere by producing 

 a vacuum, when applied. In other respects these arms are 

 nothing else but the Snail's sole divided in front into 

 lobes. The ova resemble berries, and hang attached to 

 one another in branched clusters like a bunch of grapes. 

 The Sepise possess a remarkable gland, which is com- 

 plicated with the liver, and secretes a dark brown juice, 

 which has been called ink or sepia ; it probably ranks in 

 the significance of the kidneys. 



Many are covered with a shell externally, as the 

 Nautili and Argonautse ; but in the common Sepise this 

 shell adheres within the mantle upon the back, and 

 forms a straight lamina or plate, which is sometimes 

 horny, sometimes calcareous in its texture. Ifc has been 

 called the " white fish-bone." What is regarded as the 

 dorsal side of the animal is its ventral side, because 

 upon the former lies the pallial aperture and the anus, 

 while the vitelline sac is also inserted there. 



In the form of the body, as well as in the circular 

 position of the cephalic arms, the Sepise strikingly 

 resemble their antetypes, the Acalephse and Cirripedia, 

 and their metatypes, the Asteriadae and Crustacea. 



With these animals the second stage or circle through 

 which the Dermatozoa pass, or that of the Sexual animals, 

 is closed. They require only a slight additional grade of 

 perfection, and they would pass over into another class 

 of animals. Thus were the arms to become horny and 

 articulate, they would be Crustacea; had the head a 



