SHALLOW-WATER STARFISHES 



225 



rows, twelve to fourteen each, all of nearly the same size. They 

 form clusters, as numerous or more so, and of as small size, as those 

 in var. spiculifera or mtiltispina, and more uniform in size. After 

 these twenty-five pairs of plates, those more distal suddenly resume 

 the same spatulate form and arrangement as on the other rays. 



Probably these peculiar twenty-five plates had been injured, losing 

 their spinules, and replacing them with the minute kind, just as some 

 starfishes will often replace a lost spine of large size, by a cluster of 

 granules. 



The fact that a large number of uniform small, slender spinules 

 may replace a group of few large spatulate ones, on the same ray, is, 

 however, an important fact, showing that the character of the adam- 

 bulacral spinules is not a matter of vital importance, and that it might 

 easily vary more than it usually does, even in this variable genus. 



^'\j 



Fig. 12. 



llenricia leviuscuta. var. spatutifera Verrill, type. Portion of under side; ad. adambu- 

 lacral spines; p, peractinals; m, m", inferomarginals; m'", superomarginals; ab, medio-lateral 

 pines. 



The dorsal skeleton is composed largely of elliptical and some- 

 what lunulate tliickened ossicles, rather loosely arranged, leaving 

 large papular pores, so that the surface appears rougher than in the 

 more typical varieties. The dorsal spinules are small, mostly clavate, 

 with thorny ends, much as in var. mtiltispina. 



The rows of marginal and peractinal plates are not so regular nor 

 so conspicuous as in most varieties. The inferomarginals are the 

 largest, but not so large as usual. The peractinals are much smaller 

 and roundish. 



The superomarginals are small, but larger than the dorso-lateral 

 ones, and similar to the inferomarginals in form. There are two 

 rows of intermarginals proximally, one being quite short. The 

 spinules on all these plates are numerous and very small, much as on 

 the dorsal side. 

 10 



