REPORT ON THE DEEP SEA MEDUSAE. XCV 



(" limites cathammales ") are extended into sixteen broad septal plates (" tabulae 

 cathammales "). This originates a special form of the coronal intestine, which resembles 

 the common form of the Craspedotse so strongly that the two may be confounded, but 

 which has arisen quite independently, and also differs essentially in its relation to the 

 principal intestine. Moreover, the narrow " radial canals " of the Craspedotse spring 

 immediately from the central stomach, whilst the similar "coronal canals" of the 

 Cycloperise spring originally from the distal margin of a coronal sinus, lying at the distal 

 side of four cathammal nodes. Otherwise, both the further differentiation of the radial 

 canals and their circular canals and their relation to the adjacent orders of the umbrella 

 margin show the greatest similarity in both sections. The oldest family among the 

 Cycloperise, the Flosculidae (System, taf. xxxii.) show simple radial canals which are not 

 branched inside the annular canal (as in the majority of the Craspedotse). All the 

 remaining Cycloperise (the Ulmaridse and all Rhizostomse) have branched radial canals, 

 which branch inside the annular canal (as in the Cannotidse among the Craspedotse). 

 In both cases peripheric canals of the annular canal run from it, outside it, into the 

 tentacles, rhopaba, marginal lobes, &c. (§ 135). 



§134. Coronal sinus of the Acraspedse (" sinus coronaris, canalis coronaris "). The 

 coronal sinus of the Acraspedse (cs) already mentioned forms a very important arrange- 

 ment, which has hitherto never been properly taken into account. It must not be 

 confounded with the annular canal described above, but must be considered as an original 

 and typical peculiarity of this section. Originally, it is a perfectly simple, cybndrical 

 or flattened ring in the coronal part of the subumbrella, and is formed by the entire 

 peripheric section of the coronal intestine, lying outside the distal margin of the four 

 interradial cathammal nodes (hi) or ridges (Jcs), as in Tesserantha (PL XV. figs. 2-6, cs) 

 and in Tessera (System, taf. xxi., cs), the closely allied ancestral form of all Acraspedse. 

 Although its ontogeny is still unknown, we may assume with certainty as regards its 

 phvlogeny, that it does not represent a secondary marginal communication of the four 

 broad perradial pouches, but rather the marginal portions of the originally simple 

 Scyphostoma stomach which has remained open, and lies outside the four interradial 

 cathamma (k). As the latter are originally merely small fused nodes (as in the Tesseridse 

 and Peromedusse), the intermediate perradial pouches at first merely form narrow 

 horizontal fissures. As soon, however, as the nodes become elongated concrescentic 

 ridges (as in the Lucernarida? and Cubomedusse) the insignificant horizontal fissures 

 extend simultaneously into pouches of considerable size, at the cost of the broad coronal 

 sinus, which is for the most part absorbed into them. The broad coronal sinus is thus 

 reduced into a narrow coronal canal which keeps up the communication between the 

 four large perradial pouches below the distal margin of their septal ridges (PI. XVI. figs. 

 2, 3, 12. cc ; PI. XXVL). The coronal sinus is most widely extended, and at the same 

 time undergoes a very striking modification in the Perornedusre, probably in direct 



