Fio.4'2 P. *<* * 



Histology of the body wall of Clathrina coriacea, Mont. A, body wall seen from the inside 

 in the region of the oscular rim. Ji, portion of A, showing the same three pores (p 1 , P 2 , d 

 another), but with the collar cells removed, to show the underlying parenchyma. C, same 

 portion of the body wall, with the pores p lt p.,, but seen from the outside, to show the Hat 

 epithelium. D, longitudinal section of the bouy wall, in the region of the oscular rim, fully 

 expanded. E, section of the body wall, slightly contracted. F, section of the body wall, very 

 contracted. A, 7?, and C, x 7.10 ; I>, E, F, x 500. am.c, amoebocytes ; apj.c, apical formative 

 cell ; b.f.c, basal formative cell ; c, collars of (ch.c) chonnocytes ; d.a, dermal aperture of pore ; 

 d.ep, dermal epithelium ; Jl, flagella ; g.a, gastral aperture of pore ; j>i, fft, pores ; p.c, poro- 

 cytes ; p.c.ep, porocytic epithelium ; sp, spicule ; sjt.c, spiculo cell or scleroblaut. 



