CEPHALOPODA. 439 



(480.) Turning our attention to the anatomical structure of the 

 CEPHALOPODA, we find that in all of them the exterior of the 

 body is entirely formed by an intricate interlacement of muscular 

 fibres. The sac that contains the viscera, itself muscular, is united to 

 the head by strong and largely-developed fasciculi ; the funnel (fig. 

 206, a) through which, as through a fleshy pipe, the products of 

 excretion, as well as the eggs or seminal fluid, are ejected, is form- 

 ed of a tissue similarly endowed with contractility ; while the arms 

 are composed externally of muscles disposed in various directions, 

 and moreover have their central portion occupied by strong bands, 

 which traverse them longitudinally from end to end, so that they 

 are thus gifted with all needful powers of motion, and may be 

 shortened, elongated, or bent in any direction at pleasure. 



In those species which, like Loligopsis (fig. SI 4), or Onycho- 

 teuthis (Jig. 203), have fins appended to the sides of the visceral 

 sac, these organs likewise are made up of muscular substance ; 

 and, being thus converted into broad moveable paddles, they also 

 form efficient locomotive agents. 



(481.) One important circumstance observable in the class be- 

 fore us must not be forgotten in connection with this portion of 

 the history of the Cephalopods. We may remind the student, 

 that in the vertebrate division of animated nature, to which these 

 creatures immediately lead us, the locomotive system is support- 

 ed by an internal vascular and living skeleton, composed either 

 of cartilage, as is the case in the most imperfect vertebrated genera, 

 or, in the more highly organized forms, of bones articulated with 

 each other, and possessing within themselves the means of growth 

 and renovation derived from the blood which permeates them in 

 every part. The reader will remember that, in all the classes that 

 have offered themselves to our notice, we have not hitherto observed 

 anything at all comparable to an internal osseous framework such 

 as man possesses ; dead, extra vascular shells, formed by successive 

 depositions of layers of calcareous material, or jointed cuticular ar- 

 mour equally incapable of growth, having as yet represented the ske- 

 leton, and formed the only levers upon which the muscular system 

 could act in producing the movements connected with locomotion. 



Having, however, already had abundant opportunities of seeing 

 how gradually nature proceeds in effecting the developement of a 

 new series of organs, we might naturally be led to expect in the 

 creatures before us some faint indications, at least, of our approach 

 to animals possessed of an internal bony framework, and our ex- 



