MEDUSA. I. ■ 73 



leave the periphery of the stomach, 3-3-3-3, and 11 canals reach the circnlar vessel. One of the qna- 



drants is stnnted, pressed between the neighbonrs; in connection herewith it must be remarked that ; 



the specimen is unusually highly arched. The arrangement of the canals is as follows: 



Group I. 3 canals (marked i, 2, and 3 in the figure) leave the stomach and reach the circular 

 vessel (as to No. i, see below). 



Group II. 3 canals (4, 5, 6) leave the stomach and reach the circular vessel in normal way. 



Group III. 3 canals (7, 8, 9) leave the stomach. No. 7 reaches the circular vessel normally; No. 8 

 divides into 8 a and 8 b^ both of which reach the circular vessel. No. 9 runs to the margin and reaches 

 the circular vessel so near No. i, that there is only room for 3 tentacles between the two canals. On 

 the way towards the margin No. 9 sends out a branch [x\ which, crossing No. i, runs towards the 

 margin and reaches the circular vessel between No. i and 2, nearest to No. i. 



Group IV. 3 canals leave the stomach, all very close together, and unite just outside the sto- 

 mach into one canal, which opens into the link canal x between 9 and i, nearest to No. 9. 



The arrangement of the gonads on the abnormal radial canals is sketched in the figure. 



Only in a few cases it has been possible to count the tentacles and marginal vesicles. 

 Loc. No. 3, specimen No. II (diam. 45 mm) has 442 tentacles, the distribution of which in rela- 

 tion to the 13 radial canals will be seen from the following scheme: 



Off the 13 radial canals 13 tentacles /'^^^ --' ■ • 



Group I 19 + 49 + 30 =98 — h" ,^ "^^ % 



II 25 + 34 + 27 = 86 





iO 



^--^.. •• .^^ 



11146+29+34+32 = 141 — V^.-'-.-. ^'' 



- IV 29+37 +38 = I04 - ^'■'' ^' '' '' -.V 



Total ... 442 — 



Thus the number of tentacles between two successive radial canals varies, in this specimen, from 19 to 49. 

 Loc. No. 9. specimen No. Ill (diam. 44 mm) has 16 radial canals (arrangement irregular), 428 

 tentacles, and 80 marginal vesicles, distributed between the radial canals in the following manner: 



Tentacles. . 10 29 28 16 31 23 25 28 31 20 11 36 28 36 29 31 



Marginal vesicles 1762545483369656 



Thus in the present case the number of tentacles between two successive radial canals varies from 

 10 to 36, the number of marginal vesicles from i to 9. The average number of marginal vesicles be- 

 tween two canals is 5.35, the average number of tentacles between two successive marginal vesicles is 

 5.70. The arrangement of the marginal vesicles is, however, fairly irregular, in so far as two vesicles 

 may be found immediately beside each other. 



Specimen No. IV from the same locality (diam. 56 mm) has 14 radial canals (3-3-4-4); the tent- 

 acles cannot be counted; there are 83 marginal vesicles, distributed between the radial canals in the 



following manner: 



4354785 10 379 567 



The average number of marginal vesicles between two successive radial canals is 5.9, varying from 3 to 10. 



The Ingolt- Expedition. V. 8. ■ lO 



