602 
THE VOYAGE OF H.M.S. CHALLENGER. 
and eight adradial). On the inner margin of the umbrella is a very strong coronary 
muscle, which is divided by means of sixteen subradial septa into the same number 
of quadrilateral portions. The septa are attached to the central ribs of the sixteen 
marginal lobes. 
“ Just internal to this powerful coronary muscle are attached to the subumbrella eight 
horse-shoe shaped gonades or sexual glands, which alternate with eight three-cornered 
deltoid muscles (four perradial and four interradial). In the centre there arises a large 
and almost cubical manubrium, on which four wide perradial buccal pouches ( burses 
buccales ) are separated by means of four strong interradial buccal columns. On the edge 
of the mouth are found eight oral tentacles. The cavity of the manubrium opens into 
a large central stomach, which is filled for the most part with extremely long and 
'Fig. 201. — Periphylla m/irabilis, Haeckel ; half the natural size. 
numerous gastral filaments ; and this, by means of four long perradial slits (or gastral- 
ostia), communicates with a colossal annular sinus. About half way up the stomach 
are four interradial catliammata or septal knots, in which the subumbrella and the 
exumbrella are fused. Complicated pouches pass downwards from the circular sinus to 
the umbrella margin. 
“ Periphylla mirabilis (see fig. 201), 160 mm. high, 120 mm. broad, was taken by 
the Challenger, on the east coast of New Zealand, when the trawl was lowered to a 
