REPORT ON THE DEEP-SEA MEDUSAE. 119 



The septal plates (" tabulae cathammales," figs. 3, 6, kt), are equilaterally triangular 

 plates, in which the umbral and the subumbral wall of the umbrella are firmly fused to- 

 gether, and which subsequently, as interradial septa, separate the four perradial cross 

 pouches of the bottom of the stomach and their peripheric openings, the gastral openings 

 (go) ; they therefore correspond completely to the four small septal nodes of Nauphanta 

 or of the Peromedusse (kn), and also to the four long, narrow cathammal ridges of 

 Lucernaria and of the Cubomedusas (comp. above). They are at the same time 

 homologous with the gastral tseniola of Scyphostoma, as all such septal or cathammal 

 formations have arisen from fusions of the umbral and subumbral parts of these tseniola. 

 In most Discomedusse (Semostoma and Rhizostoma) the four primary cathamma have 

 entirely disappeared, and the gastral filaments are consequently placed on the subumbral 

 gastral wall. In Atolla the septa are distinguished by their broad flat form ; each 

 cathammal plate bears a two-limbed phacellus (as in Periphema) and forms an equilateral 

 triangle, whose point is directed centripetally towards the centre of the stomach, whilst 

 the two limbs, concavely bent inwards, are beset with a row of short, closely com- 

 pacted gastral filaments (figs. 3, 5,/). The abaxial (tangential) base of the triangle 

 measures 12 mm., its (interradial) verticle line 6 mm. The limbs of each two adjacent 

 triangles pass externally into one another in a semicircular arch, which is only 

 interrupted in the middle by the perradial gastral opening (go). A red-brown arched 

 line, into which numerous radial, rust-red lines covering the surface of the equilateral 

 triangle open, runs towards the exterior, a millimetre apart from, and parallel to, the 

 concave limbs of the triangle (or the line of insertion of the gastral filaments, /). 

 These fine rust-red lines are sinuated, tube-shaped glands, which open into the gastral 

 cavity at the rust-red concave line of the limbs, and which we may regard as central 

 liver glands. They have the same formation as the rust-red, peripheric adocular canals, 

 which we shall presently recognise in the rudiments of rhopalar coronal pouches, which 

 have undergone retrograde formation. The narrow hollow space of the simple tubes is 

 lined by a layer of red-brown, irregularly polyhedrical, glandular cells. Masses of 

 yellowish and red-brown pigment granules and fat granules lie round the clear 

 spheroidal nucleus, filling the whole protoplasm. 



The gastral filaments (f) are placed, compacted in a row, on the two limbs of the 

 triangular septal plates, which may, therefore, be regarded as flattened tseniola. If we 

 suppose these tseniola separated from the umbrella cavity by hollows formed of four 

 interradial conical subumbral funnels, we have the same condition as in Periphema (PI. 

 XXIV. fig. 1). The four centripetal points of the tseniola, from which the four pair of 

 phacelli run out so that the two rows of filaments of each pair diverge simultaneously to 

 the outside and to below, comport themselves in essentially the same way in both 

 species. They are, however, much less strongly developed in Atolla ; only from fifteen to 

 twenty filaments are placed in a row on each limb of the phacelli, so that their aggregate 



