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series of loops down the edges of the mesenteries (Fig. II.). 

 The character of looping depends on the state of retraction of 

 the polyps, iout normally alternates from side to side. Below 

 they end in a massed series of larger loops, irregularly 

 arranged. The end of the filament is not free. The mesentery 

 between the massed portion of the filament and the longi- 

 tudinal muscles is no doubt enormously extensile, but there 

 is no part which could be shot out as an acontium (see 

 PI. Ill , fig. 17). The filaments of the secondary mesenteries 

 commence right from their attachment to the stomodoeum 

 or peristome, and, enlarging somewhat, extend down straight 

 for some distance, still deeper forming similar loops. 



Generative Organs. — The presence or absence in an indi- 

 vidual of generative organs on any mesentery depends 

 entirely and solely on its size. In the youngest male state 

 single round or oval acini are found just behind or sometimes 

 a little below the massed end of the mesenterial filament. In 

 the next stage a few widely separated masses may be seen,, 

 forming with the thickened endoderm a narrow band. This 

 increases in length and breadth, so that in the largest mesen- 

 teries an oval-shaped mass, 5 mm. long by i"5 mm. broad, is 

 found. The whole then consists of closely-packed sper- 

 magens, which vary considerably in size and shape, some 

 being branched, others round or oval, and yet others nearly 

 polygonal. 



The ovaries are similar in size and position to the testes. 

 In the ripe condition on the larger septa they have a row of 

 up to about seven ova, the end ones oval in shape, the central 

 one round, but all flattened where they touch one another. 

 Fresh ova — at first small round bodies with no food yolk — 

 generally appear in the structureless lamella each between a 

 riper ovum and the free edge of the mesentery, but in one 

 case, where the central of three nearly ripe ova seems to 

 have been dehisced, three small ova have appeared in its 

 place. 



In 1 1 polyps of dredging No. 4 and 3 of No. 5 that I have 

 examined the whole or main bulk of the mass is testicular on 

 the primary mesenteries. On all the secondary mesenteries, 

 where the development may be traced, the whole is always 

 so. In one series of sections across a polyp of No. 4 fcalicle 

 17 mm. long) I have found in the inner part of the testicular 

 masses on the primary mesenteries a few relatively small 

 isolated ova without food yolk. In one mesentery of a still 

 larger polyp of the same dredging there are three ova on the 

 inner edge of the testicular mass at its top end behind the 

 massed loops of the mesenterial filament (PI. Ill, fig. 17) and 

 in all the other primary mesenteries of the same polyp ova 

 were found as well. In two small polyps of No. 3 the mass is 



