ATLANT. DEEP-SEA EXPED. 1910. VOL. III.] 



ANTHOMEDUSAE AND LEPTOMEDUSAE. 



11 



folded lips, separated by slight incurvations, not by deep 

 incisions. About 12 narrow radial canals issue from the 

 periphery of the stomach 1 ). In two of the individuals the 

 radial canals are nearly equidistant at their origin; in the 

 other specimens they originate in a somewhat irregular 

 manner (se below). In the dorsal (umbrellular) wall of 

 the stomach there is a number of ciliated grooves, form- 

 ing a cross, the four arms of which are soon divided 

 into three or four branches, each leading to one of the 

 radial canals. They are centripetal continuations of the 

 dorsal wall of the radial canals and indicate, that there 

 are really four groups of canals, though in the full-grown 

 medusa the canals are completely separated outside the 

 periphery of the stomach. The radial canals are straight 



and narrow and connected with a narrow ring-canal. The 

 distal ends of the radial canals are not always equidistant 

 (see below). The gonads are situated along the radial 

 canals, forming a narrow, somewhat folded band on each 

 side of the canal, leaving both ends free, commencing 

 2—7 mm. from the periphery of the stomach and ending 

 1 — 2 mm. from the ring-canal. There is a large number 

 of tentacles, as many as 350, fairly long and contractile. 

 There is one fine cirrus (more seldom two cirri) between 

 each successive pair of tentacles. The marginal vesicles 

 are large open folds of the velum, containing a large 

 number of lithocysts. The marginal vesicles are present 

 in a number of 3 — 5 between each successive pair of 

 radial canals. The velum is narrow, 2.5 — 3 mm. broad. 



Table showing Variation of Halopsis ocellata. 



Stat. 



Length 

 of wire 



Diameter 

 of bell 



Diameter 

 of stomach 



Number of 

 radial canals 



Proximal part 

 of radial canals 

 free of gonads 



Distal part of 



radial canals 



free of gonads 



Number of 

 tentacles 



94 



1500 m. 



32 mm. 



8 mm. 



12 



4 — 5 mm. 



1 — l.r, mm. 



ca. 220 



97 



50 - 



-10 - 



8 - 



12 



ca. 6 



2 



- 260 



— 



— - 



35 - 



9 - 



12 



6—7 - 



1 



- 350 



98 



200 - 



40 - 



8 - 



13 



4—5 - 



1-1. 5 - 



- 275 



101 



200 - 



28 - 



8 - 



13 



ca. 4 



1 



- 270 



— 



1000 - 



22 - 



7 - 



11 



ca. 2 - 



1 



- 200 



The specimens, preserved in formalin, are colourless. In order to illustrate the variation of the mode of origin 



Variation. — The table gives a view of the variation of the radial canals, I have figured the stomachs of the 



of the 6 specimens brought home by the "Michael Sars". six specimens seen from the aboral side. — In the specimen 



Fig. l. 



Fig. 2. 



It will be seen, that the diameter varies from 22 to 40 from stat. 94 (textfig. 1) the canals originate in groups 



mm., the number of radial canals from 11 to 13, the 

 number of tentacles from about 200 in the smallest spec- 

 imen to about 350 in one of the larger individuals. 



') I have seen specimens from Iceland with 16 radial canals. 



of 2—3 — 3 — 4, altogether 12 canals. The distances be- 

 tween the canals when leaving the periphery of the stomach 

 are very different. The number of tentacles between two 

 successive radial canals varies from 12 to 27. — In the first 

 of the specimens from stat. 97 (textfig. 2) the grouping 



