392 



TEGUMENTARV ORGANS 



by a protomorphic layer consisting of a homogeneous substance 

 containing endoplasts (c), which sometimes adhered to the enderon, 

 sometimes to the hard integument, when the latter was detached. 

 3. Superficial to this, was the chitinous layer of the integument (c) 

 composed of a number of laminae of great delicac}', and not more 



than -g^-inro- of ^n inch apart. The 

 lamina 



deep lamina were much softer 

 than the superficial, and the outer- 

 most lamina of all was hardest, 

 and of a brownish colour, consti- 

 tuting the structureless epidermis 

 of Carpenter and Lavalle. 



In section, the deep laminae (b) 

 presented only an indication of 

 perpendicular fibrillation ; but this 

 became more marked superficially, 

 the outer part of the section ap- 

 pearing closely striated. The deep 

 laminae, when stripped off, pre- 

 sented no definite structure, but 

 they readily fell into plaits ; while 

 the superficial laminae appeared 

 dotted over. I sought in vain for 

 any appearance of endoplasts in 

 the deep layer, where, however, 

 had they existed, they must have 

 been readily detected ; and I 

 therefore conclude, that the chiti- 

 nous lamellae are formed from the 

 subjacent ecderon, by a process of 

 excretion. It should be remarked, 

 however, that a minute polygonal 

 areolation is observable at times 

 upon the most superficial " epider- 



FlG. 



312. — A to E, from the crab ; 

 the shrimp. 



F, o, from 



mic " layer. I do not know from what cause this proceeds, but the 

 areola are certainly not cells. 



Such is the structure of the soft interarticular integument, in which 

 I could find no calcareous matter. If it be traced into the hard calcified 

 shell, the only alteration observable is, that a dark calcareous deposit 

 takes place, the earthy matter being infiltrated, as it were, through 

 the laminae. The deposit affects, however, only the middle layers, 

 the extreme outermost being left as the " horny epiderm " ; while a 



