10(5 



Dr. J. E. Duerdcn on tin 



the relationships of the complete and incomplete mesenteries, 

 it is clear that each polyp will, upon separation along the 

 axial plane, possess twelve mesenteries with the paired 

 arrangement exactly as in the adult. 



Another polyp exhibited thirteen complete mesenteries with 

 several alternating incomplete members, associated with one 

 stomodffium, while on the other stomodaium were inserted the 

 normal eight. Several large ova were developed in the single 

 connecting mesentery of one polyp, while they were absent 

 Irom the remaining mesenteries. 



We may now return to a consideration of the median 

 mesenterial strands connecting the two stomodajal invagina- 

 tions. In some polyps two of these are found to extend as 

 vertical partitions throughout the length of each stomoda^um, 

 and at the uppermost extremity of the polyp they pass along 

 the narrow central portion of the disk intervening between 



Fig. 7. 



Transverfe section tLrougli a large pol^-p projecting- all the way round 

 from the general surface of the colony. Only two mesenterial pairs, 

 A, B, occur within the ventral entoccele, while three pairs, C-E, 

 have been added within the dorsal entoccele. 



the two oral apertures. Sometimes only one may be present, 

 extending the whole way ; in others the partition has disap- 

 peared above, but is complete below ; while again, as in 

 fig. 6, both partitions may be wholly absent, each presumably 

 represented by the two distinct pairs of mesenteries {E, E; 

 F, F ) which stretch from the stomoda^ura to the dorsal region 

 of the body-wall. 



That each connecting strand actually becomes divided into 



