22 



McMURRICH 



least it was decamerous. To illustrate the irregularity which 

 exists, Fig. 1, representing the arrangement of the mesenteries 

 in the specimen with two siphonoglyphes a little below the mid- 

 dle of the stomatodseum, is appended. 



Attention may be called to one interesting irregularity in this 

 specimen, and that is the development of two pairs of mesenteries 

 in the endoccel of one of the perfect pairs. 



The longitudinal musculature of the perfect mesenteries is 

 fairly well developed (Fig. 14) and there is a well-marked parieto- 



FlG. I. 



basilar forming a fold upon the peripheral portion of each mesen- 

 tery. Both inner and outer mesenterial stomata are present. 

 Reproductive organs may apparently be developed on any of 

 the mesenteries, with the exception of the directives and of the 

 incomplete cycle, but in the two specimens examined minutely 

 with this point in view they are not distributed with perfect 

 regularity, some mesenteries of every cycle lacking them. 



There is no doubt but that in many respects of structure this 

 form approaches closely to Urticiiia cmssicornis, the differences 



