254 RITTER AND CROCKER 



a limitation in the number of these structures does not obtain in 

 all multiradiate stars, for in Solaster cndeca^ at least, the only 

 other one which we have been able to examine with reference 

 to the point, the number, though not quite double that of the 

 number of rays, was yet not reduced as in Pycnofodia. 



Having noted the strict bilateral symmetry of the budding re- 

 gions, and the consequent bilaterality which this imparts to the 

 animal during the whole period of ray multiplication, we may 

 now inquire whether anything of this symmetry is impressed 

 upon the internal parts, and [whether it anywhere persists 

 through the entire life of the animal. 



We find that the following structures are disposed more or 

 less bilaterally, with A IV as the axis of symmetrj^ ; the anus, 

 the intestinal coeca, the racemose glands, and the apical radial 

 muscle bands. 



The anus is situated excentrically in this line and somewhat 

 toward ray A. This, it will be recalled, corresponds to its po- 

 sition in the five-rayed star; /. ^., it is in the interradius next, 

 clockwise, to the one containing the madreporite (fig. 4). 



The intestinal coeca are well developed, often having as 

 many as ten tubules. These all lie toward A, in the adult 

 often even extending between the interradial septa of this ray, 

 though frequently also a few tubules get pushed into the bases 

 of the adjacent rays, but they never get far away from A. 



The racemose glands have kept a symmetrical arrangement. 

 Invariably a pair is found in the interradii V-IV, IV-III, and 

 III-II. Also a gland is found in the interradius on each side of 

 A, and a gland in the next interradius on the right, and some- 

 times one on the left. Ten is the largest number found, six of 

 which belonged to the group of rays II-V, and four to the re- 

 gion of A. While, then, these structures are not perfectly bi- 

 lateral in arrangement, they are very nearly so (fig. 7). 



The point of radiation of the muscles is in the same line and 

 very near the anus (fig. 6). Their arrangement is as follows : 

 Of rays III, IV and^V, each has its own distinct band, arising 

 from the common center ; I and II have bands arising from the 

 same center, btit from these are given off bands to the secondary 

 rays of their corresponding sides, the older ones being most sep- 

 arated (fig. 6). 



