REPORT ON THE DEEP-SEA MEDUSAE. 121 



The marginal corona of pouches, the second principal section of the peripheric 

 coronal intestine in Atolla, presents at first sight very peculiar conditions of formation, 

 varying considerably from those of all other Cannostomas. From the distal margin of the 

 coronal sinus (cs) nineteen to twenty-two broad, oval, coronal pouches run out, which pass 

 into the tentacles (fig. 3, to the left, below, bt). Their distal half is cleft into three 

 narrow branches, of which the middle one (ct) enters a tentacle as tentacular canal, whilst 

 the two lateral enter the inverted margins of the two adjacent rhopalar pedalia (ck). Between 

 each two coronal pouches, however, a group of three narrow, caecal, radial canals, which 

 lie on the subumbral side of the rhopalar pedalia, run out from the coronal sinus. The 

 middle one of these csecal canals is longer and runs as rhopalar canal (co) directly to the 

 rudiment of the sense club (or), whilst the two lateral, shorter adocular canals (ex) already 

 end before reaching the distal margin of the coronal muscle ; they are coloured rust-red, 

 and show the properties as the glandular canals of the septal plates already described. If 

 we compare this peculiar condition with that of the closely allied genera Nauphanta 

 (Pis. XXVIL, XXVIII.) and Collapsis (System, taf. xxix.), we see that the last-named 

 group of narrow parallel csecal canals represent a rhopalar pouch, which has undergone 

 retrograde formation, and is cleft up to its original base into three canals ; the middle 

 one of these (co) corresponds to a distal rhopalar pouch, whilst the two lateral (ex) 

 rudimentary " rhopalar lobe pouches " are transformed into glandular canals. These never 

 enter the true marginal lobes, but are limited to their common basal part, the rhopalar 

 pedalium. The tentacular coronal pouches (bt), which vary much less from the usual 

 conditions and send out their two side branches into the marginal lobes, remain 

 separated from the rhopalar pouches by a broad fused lobe clasp (kl), which projects 

 centripetally to the distal margin of the coronal sinus. This peculiar modification of the 

 marginal corona of pouches is probably in corelation with the retrograde formation of the 

 sense clubs. 



Genitalia (figs. 2-4, g). All the five specimens of Atolla wyvillii examined were mature 

 females, three of whom had almost completely emptied out their ova. The ovaries (s) 

 form eio-ht adradial, broad, flat, elliptical pouches, lying inside the subumbral wall of the 

 coronal sinus, and alternating with its deltoid muscles. They are not, however, regularly 

 distributed as in the closely allied Collajisis (System, taf. xxviii. figs. 1, G). But as the 

 four stronger interradial deltoid muscles (mcl") are considerably broader than the four 

 weaker perradial (mcV), the two genitalia originally belonging to one interradial pair 

 lie further from each other, whilst the two reproductive glands almost touching each 

 other, which lie on the two sides of a perradial deltoid mass, belong to two different 

 pairs. The eight ovaries appear to be flattened, elliptical pouches, which be freely on the 

 outer, ectodermal, subumbral wall of the coronal sinus, and project freely as its pouched- 

 shaped evaginations into the umbrella cavity (fig. 2). Closer examination shows, 

 however, that they are rather enclosed in the hollow space of the coronal sinus, and that 



(ZOOL. CHALL. EXP. PART XII. 1881.) M 16 



