46 INVERTEBRATE ANIMALS. 



Group 132.— Family ARGON AUTID^E. Argonaut, Paper- 

 Nautilus. The beautiful shell of the female Argonaut is 

 secreted by the extremities of the dorsal arms, which are 

 disciform. The animal is not attached to the shell, but 

 sits in it, clasping the sides with its webbed arms. 



IT Very large specimen of A. argo, and examples of 

 four other species. 



Upper Compartment. 

 Drawings of the female Argonaut with its shell. 

 Preparation in liquid of male Argonaut, shew- 

 ing the hectocotylised arm. 



^toelftlj CnbU €mt^ 



If VERMES he adopted as a Siih-kingdom, this and the 

 following eight table-cases shoidd succeed the fourth table- 

 case, and the MOLLUSC A take tlielr places. 



Sub-kingdom ANNULOIDA. 



Animals possessing a distinct nervous system, a 

 water vascular system, and a food canal shut 

 off from the body cavity : body of the adult 

 having its somites (merosomes) disposed 

 pseudo-radially, without true segmental division. 



As the principal departure from the ordinary method 

 of arrangement occurs at this point, it may be proper 

 for the Writer to mention, by way of explanation, that 

 he cannot bring himself to regard the high development 

 of special organs in the Cephalopoda, due probably to 

 the absence of morphological ohstructions, aa in any wise 

 equivalent in importance even to the first prefigurements 

 of the great annulose type ; in which many somites, 

 each in itself an individual of a lower grade, unite 

 as constituents, first of a type with an exo-skeleton 



