POSITION AND DISTRIBUTION OF SAGARTIA LUCI^. 



731 



paralleled by some membei'S of the genus Aijitasia ; neither of 

 these- genera, however, belonging to the same subfamily as 

 Sagartia. 



When one comes to consider the arrangement of the mesen- 

 teries, difficulties are at once encountered, because of the tendency 

 of the species to repi-oduce by longitudinal fission. Some half- 

 dozen individuals of which serial sections were prepared all 

 showed irregularities in the arrangement of the mesenteries that 

 may be reasonably attributed to this process, but nevertheless, 

 they permit of inferences as to what the arrangement may have 

 been before fission occurred. Three individuals may be taken as 

 examples (text-fig. 2). In each of these in sections through the 

 middle of the column there was a deep siphonoglyph at one end 

 of the long axis of the stomoda?um, and to this a pair of directive 

 mesenteries with Avell-developed muscle pennons was attached. 

 Opposite it was a second siphonoglyph which was relatively quite 

 shallow, and to this a second pair of directives was attached, the 



Text-figure 2. 



Diagi'aras showing the arrangement of the mesenteries in three individuals 

 from Woods Hole, Mass. 



muscle pennons of these being, however, very imperfectly de- 

 veloped. On either side of the fully-developed directives there 

 were representatives of two cycles of imperfect mesenteries, and 

 then came on either side a pair of perfect ones. So far the 

 arrangement is quite regular except for the imperfect develop- 

 ment of one siphonoglyph and its directives, but in two of the 

 individuals, one member of each of the lateral pairs (II. and VI.) 

 was decidedly less developed than the other. In these same two 

 individuals (B and C) the pair II. is succeeded by another perfect 

 pair (III.) poorly developed, and next this is the second pair of 

 directives (IV.), no imperfect pairs occurring in the interspaces 

 between II. and III. and III. and IV. Similarly, another pair 

 of perfect mesenteries (V.) with fully-developed muscle pennons 

 occurs between IV. and VI., and while no imperfect pairs occur 

 in the interval between these and IV., in the interval on the other 

 side there is in one individual a single small pair and in the 



