REPORT ON THE DEEP-SEA MEDUSA. XCl 



§ 129. The four perradial pouches of the Ephyroniae. In the second and younger 

 sub-section of the Acraspedae, the Ephyroniae, the coronal intestine strikes out a direction 

 of formation which contrasts thoroughly with, and differs essentially from that presented 

 by the first and older sub-section, the Tesseroniae. Whilst the four primary radial 

 pouches of the coronal intestine in the Tesseroniae are always very large, and form its 

 principal component part, in the Ephyronias they appear to be wanting, or only to exist 

 as small rudiments : up till now they have been completely overlooked in the Ephyroniae 

 or Discomedusae, and not taken into account by any author on Medusae. The two deep- 

 sea Cannostomae, Nauphanta (Pis. XXVIL, XXVIII.) and Atolla (PL XXIX.), are of 

 great importance for comprehending their formation ; from their size they show the 

 primitive formation more clearly than the known small Nausithoe, in which the four 

 septal nodes are certainly also present but are very small, and have hitherto been 

 invariably overlooked. In all the Cannostomae named (and probably in all Discomedusae 

 of this sub-order) four interradial septal nodes (hi, PI. XXVIL fig. 3 ; PL XXVIII. figs. 

 14, 15 ; PL XXIX. figs. 3, 6) are found in the upper part of the coronal intestine. They 

 correspond completely, in situation and significance, to those of the Tesseridae (PL XV. 

 figs. 2-6, Jen), and the Periphyllidae (Pis. XX.-XXIV., hi). In Atolla (PL XXIX.) these 

 important four interradial cathammal nodes are triangular and strongly flattened, whilst 

 in Nauphanta (Pis. XXVIL, XXVIIL), and also in Nausithoe, they are very small, and 

 have as yet been taken no notice of. In their transverse sections, however, they show 

 distinctly the important cathammal plate or endodermal lamella ()'k), the fused plate 

 between the gelatinous body of the notumbrella and the supporting plate of the 

 ccelumbrella (PL XXV. fig. 8, dk). The ventral wall of the coelumbrella and the dorsal 

 wall of the notumbrella are fused by means of these four interradial fused nodes ; 

 between these four perradial transverse fissures remain, which represent the four 

 rudimentary, very much shortened radial pouches, and whose proximal margin is at 

 the same time to be regarded as a "gastral ostium" (go). If we suppose these nodes 

 prolonged interradially downwards in the form of narrow septal ridges, the underlying 

 coronal canal or coronal sinus (cs) will be thereby divided into four broad, long, 

 radial pouches, resembling those of the Lucernaridae (Pis. XVI., XVII. , bp). In the two 

 other sub-orders of the Discomedusae, the Semostomae and Rhizostomae, the four primary 

 septal nodes, which were originally present, appear to have undergone retrograde 

 formation, and become lost, whilst the Cannostomae have kept them faithfully up to the 

 present day ; the Cannostomae — which in many respects still resemble the Tesseroniae — 

 being the ancestral form of the Discomedusae, from which the Semostomas have been 

 developed later (and the Rhizostomae still later from the Semostomaa). In the 

 Ephyrula larva of the latter, the four primary gastral filaments, probably indicate the 

 spot formerly occupied by the predecessors of the septal nodes. The four cruciate 

 pouches of the central stomach already described, may perhaps be considered as partly 



