SHALLOW-WATER STARFISHES 235 



The dorsal surface is thickly covered with small, rough pseudo- 

 paxillae, which mostly surround large papular pores, each usually 

 with a single papula. The papular pores are numerous and are 

 found on nearly all parts, even between the peractinals and adambu- 

 lacral plates. Most of the pseudopaxillae are roundish or elliptical 

 and bear from six to twelve spinules; the larger ones are narrow- 

 oblong, and have about two rows of spinules, often amounting to 

 twenty to twenty-five. Frequently the pseudopaxillae are crowded 

 and appear to blend together in circles around the papulae. The 

 spinules are elongated, slender, with rough, thorny or spiculose tips. 



The adambulacral plates and spines are relatively large; each 

 plate bears a rather short intra-ambulacral or furrow-spine, and a 

 transverse row of four to six on the actinal side. The first three of 

 these are larger and divergent, elongated, and obtuse. The others 

 are smaller and graded. 



The inferomarginals form regular rows; they are strongly com- 

 pressed and bear about twelve to twenty small, slender spinules. 

 The superomarginals are smaller, oblong, oblique, compressed, with 

 similar but fewer spinules, like those of the dorsals. The peractinals 

 are small and extend to about the distal fourth. They have four to 

 six spinules ; they are close to the adambulacrals ; one or two very 

 short intermarginal rows, or a small group, may be present close to 

 the base of the ray. They are similar to the superomarginals and 

 dorsals in spinulation. 



The central part of the disk and oral region are deeply withdrawn, 

 forming a funnel-like pit. The interradial actinal areas are closely 

 folded inward, and about eight or nine adambulacral plates in each 

 row are included in the incurved portion of the actinal surface. 

 These plates and their spines rapidly decrease in size adorally, those 

 near the jaws being less than half as large as the eighth or ninth. 

 There are two short, stout, apical peroral jaw-spines, and about six 

 small epiorals. 



This species or " form " is easily distinguished by its large, 

 swollen disk and short rays, and by the deeply sunken oral region. 



The dorsal surface is nearly as in H. borealis, except that the 

 ossicles are usually smaller and the spinules are more numerous and 

 in smaller clusters, and often stand in small, rounded or oblong 

 groups around the papulae. 



The marginal, actinal, and adambulacral plates and spines are 

 nearly the same as described under H. borealis, but in some speci- 

 mens the supermarginal row of plates is not separated, proxi- 



