24 ORGANS OF LOCOMOTION. 



ted : the bile is poured into this cavity by two canals. The 

 liver is very voluminous, sometimes simple, and sometimes di- 

 vided into two or more lobes : its colour is reddish yellow, and 

 its texture very soft. The intestine, which arises very near the 

 cardiac orifice, is simple, and communicates, at a short distance 

 from the pylorus, with a glandular pouch which seems to be ana- 

 logous to the pancreas ; and, after making several curves, this 

 tube empties into the branchial cavity, at the base of the funnel 

 through which the water escapes that has served the purposes of 

 respiration. 



8. In dibranchial cephalopods, there exists in the neighbour- 

 hood of the liver another very remarkable secretory organ, which 

 produces in abundance a blackish liquid, called ink ; the excre- 

 tory duct of this gland (fig. 10, e) empties -into the intestine near 

 its extremity, and, when the animal is in danger, pours out, 

 through the funnel or tube, enough of this liquid to darken the 

 water around, and thus conceal itself from the sight of its ene- 

 mies. The ink of one of these cephalopods the cuttle-fish is 

 employed in painting, under the name of sepia ; and many au- 

 thors suppose that the Indian ink of the Chinese is an analogous 

 substance, though it appears the material commonly used in the 

 manufacture of Indian ink is nothing but very finely powdered 

 charcoal. The tetrabranchial cephalopods do not possess any- 

 thing similar. 



9. It has been already stated that mollusks have no solid, ar- 

 ticulated frame within their body, similar to the skeleton of ver- 

 tebrate animals. In the cephalopods, however, we find traces of 

 something analogous; for there exists in the head a cartilage 

 which not only protects the brain, but enlarges the head in differ- 

 ent directions, to furnish points of insertion to the principal mus- 

 cles of the animal. 



10. The disposition of the organs of locomotion and prehen- 

 sion, which are fixed around the mouth, varies in these animals. 

 In the dibranchial cephalopods, there is a crown of eight or ten 

 large fleshy tentacula, the inferior surface of which is furnished 

 with suckers, like cupping-glasses, by aid of which they fix them- 

 selves very strongly to bodies that they embrace (see fig. 7, page 

 19). In the tetrabranchial cephalopods, on the contrary, these 

 appendages, though very numerous, are slender and unprovided 

 with suckers. 



11. The organs of the senses are most perfect in the dibran- 



8. What is sepia ? How is it formed ? What is Indian ink ? 



9. Have cephalopods anything resembling an internal skeleton ? 

 10. What is the disposition of the organs of locomotion? 



