REPORT ON" THE DEEP-SEA MEDUSAE. XCvii 



perradial pouches, of whose long septa the distal part only remains (in the form of four 

 small nodes). Among the Ephyroniae (or Discomedusas), the Cannostomaa only show 

 similar conditions ; Nausithoe and Ncmphanta (Pis. XXVIL, XXVIII.), and also 

 Collaspis and Atolla (PI. XXIX.) have preserved the coronal sinus (cs) along with the 

 four primary cathamma (k) and their four intermediate perradial fissures up to the 

 present time. In the other Ephyroniae (Seniostomae and Khizostomae), the four 

 cathamma are dissolved and have disappeared ; the coronal sinus is consequently merged 

 in the central stomach of which it forms the peripheric part. 



§ 135. Peripheric processes of the gastrovascular system. In many lower Medusae of 

 both sections, the formation of the gastrovascular system is limited to the essential portions 

 of the principal intestine and the peripheric coronal intestine already described. In the 

 majority of Medusae, however, there are additional, accessory processes of the vascular 

 system, which serve for the nutrition of the peripheric organs. Such pre-eminently are 

 the nutritive canals of the marginal organs, the tentacles and the organs of sense : they run 

 out partly immediately from the distal ends of the radial canals or pouches, partly from 

 the marginal coronal canal, connecting the latter among the Craspedotae; besides these, 

 special centripetal canals are sometimes developed, which grow out from the annular canal 

 towards the middle of the subumbrella, and serve for the nutrition of the latter. They are 

 found almost exclusively in the order of the Trachomedusae, and are usually simple with 

 caecal proximal ends : e.g., as in Pedis among the Pectyllidae (PI. V. fig. 2 ; PL VI. fio-s. 

 11, 20), in Olindias among the Petasidse, and in part of the Geryonida? (System, taf. xv. 

 figs. 9, 10 ; taf. xviii. figs. 5, 8). The Cannotid Spirocodon is distinguished by dendritic 

 ramification of the centripetal canals (System, p. 636, No. 588). The most remarkable of 

 these peripheric processes of the vascular system among the Acraspedae are those which 

 pass into the marginal lobes or the velarium formed by their fusion. The velar canals of 

 the Cubomedusae (PI. XXVI. fig. 8), the lobe canals of the Discomedusa? belong to this 

 category. In the Typhloperiae (§ 132), as in the Cubomedusaa, the latter never form 

 anastomoses, whilst in the Cycloperiae (§ 133) they form by repeated anastomoses a 

 vascular network, varied in form, which often occupies not only the marginal lobes but a 

 large part of the subumbrella (PI. XXXII. fig. B, §117). Finally, there are noticeable 

 irregular gelatinous canals, sometimes simple, sometimes branched (" canales endo- 

 collares ") which in the larger and older Discomedusae grow out extensively from the 

 coronal intestine into the gelatinous substance of the body (e.g., Chrysaora, Cyanea, 

 Pilema, Crambessa). 



§ 136. Peripheric openings of the gastrovascular system. In the majority of all 

 Medusae the central mouth forms the only opening of the gastrovascular system. In 

 single Medusae of both sections, however, there are also small peripheric openings, which 

 are in every case of a secondary nature. The most important of these are found on the 

 umbrella margin, and may be generally termed marginal pores (" pori marginales "). 



(ZOOL. CHALL. EXP. PAKT XII. — 1881.) M n 



