REPORT ON THE DEEP-SEA MEDUSAE. xciii 



latter), in the Ephyroniae or Discomedusae they form the principal component part of the 

 coronal intestine. They differentiate here in a great variety of ways. The more the four 

 primary perradial pouches in the Discomeclusse become subsidary, the more extensive are 

 the numerous and voluminous marginal pouches which take their place ; in spite of this, 

 the latter must be regarded here as originally distal processes of the former. It is 

 important to distinguish the original from the later formations among the manifold and 

 protean differentiations undergone by the corona of marginal pouches in the different 

 groups of Discomedusaa. We consider the simple eight principal radial pouches (four 

 perradial and four interradial) which appear universally in the Ephyra larva of the 

 Ephyronise, and then pass into the eight typical sense clubs or rhopalia (and which are 

 therefore called sense pouches, ocular pouches, or rhopalar pouches (" bursas rhopalares," br) 

 as the primitive marginal pouches of this order. They correspond to the eight coronal 

 pouches of the Pericolpidae (among the Peromedusse), of which four likewise lie perradially 

 and four interradially, the former passing into the tentacles, the latter into the rhopalia 

 (woodcut, fig. 0, p. xcvi.). Eight adradial alternating tentacle pouches, which pass into the 

 eight typical tentacles of this order (Pis. XXVII., XXVIII., bf), are, however, immediately 

 added to these eight principal rhopalar pouches. The characteristic corona of marginal 

 pouches in most Ephyronige, therefore consists of sixteen coronal pouches ("bursas coro- 

 nares," be), of which the eight principal rhopalar pouches are, however, phylogenetically 

 older than the eight adradial tentacle pouches. All the sixteen pouches are separated by 

 sixteen narrow septa or fused streaks ; these sixteen subradial cathammal ridges correspond 

 to the sixteen subradial peronia of the Periphyllidas. The sixteen coronal pouches of the 

 Discomedusse do not, however, communicate like those of the Periphyllidae by a marginal 

 festoon canal (below the distal ends of the cathammal ridges), but remain originally 

 completely separate and end csecally. Many Ephyridse still show this original condition, 

 as the eight large or principal pouches end csecally in the eight sense clubs, the eight 

 smaller adradial pouches at the bases of the eight tentacles. The varied peripheric 

 pouch formations of the Discomedusse may all be derived from this primary condition as 

 secondary modifications and more recent developments. 



§ 132. Typhloperiae, or Ephyronias without annular canal. According to the preceding 

 view, the peripheric pouch corona of the DiscornedusaB consists originally in all Acraspedae 

 of this order (as in all their Ephyrula larvae at the present time) of sixteen simple, caecal 

 coronal pouches, separated by sixteen narrow subradial cathammal ridges, and from which 

 the eight principal pouches (four perradial, four interradial) pass into the rhopaba, and 

 the eight adradial into the tentacles. As regards the further differentiation of this 

 originally simple pouch corona, there are two different types in this order so rich in 

 forms ; the older, conservative type, we shall term for brevity, the Typhloperiae, the 

 young and more progressive type the Cycloperiae ; the latter is distinguished by the 

 accprisition of a second circular canal, which is still wanting in the former. Of the 



