STARFISHES OF THE PHILIPPINE SEAS. 439 



line at the ambitus. The general facies of the two forms is different. 

 Both, however, have 3 small spinelets in the furrow, and numerous 

 subambulacral spines. In densispiyia the latter are more numerous, 

 however, and the furrow margin forms a more prominent angle. 



This species differs from H. praestans (Sladen) in lacking the 

 large primary meshes of the abactinal skeleton (which resemble those 

 of H. miitans) and in having more than 1 spinelet on the furrow face 

 of the adambulacral. Superficially at least there is considerable 

 similarity between the actinal surfaces of the 2 forms. 



HENRICIA ARCYSTATA Fisher. 



Plate 118, figs. 4, 5 ; plate 119, fig. 4 ; plate 120, fig. 2 ; plate 132, fig. 4. 

 Henricia arcystata Fisheb, 1917&, p. 91. 



Diagnosis. — Similar in general appearance to H. mutans (Koeh- 

 ler), but with shorter rays, 2 or 3 spinelets on the furrow face of 

 the adambulacral plates (instead of apparently 1), and with a dis- 

 tinct series of T-shaped inferomarginals and crescentic superomar- 

 ginals. R = 72 mm., r = 10 mm., E = 7.2 r; breadth of ray at base, 

 9 to 10 mm. Rays slender, depressed, curved at the end, tapering 

 very slightly. 



Description. — Eays slender, depressed, and of the general form 

 of those of H. mutans (but shorter), and the primary meshes of the 

 skeleton usually smaller on the disk and proximal fifth of ray as 

 in that species. In a specimen from station 5536 the meshes are as 

 large on the disk as on the rays. These large meshes are irregular 

 and contain 1 to 5 or 6 smaller plates which are not so prominent as 

 the others, and form a secondary network separating fairly conspic- 

 uous papulae, of which there are 1 to 5 or 6 in each primary area 

 on the ray. The rather narrow skeletal pieces bear about 3 or 4 

 rows of delicate, sharp, very small spinelets. 



Extending about four-fifths the length of ray adjacent to the 

 adambulacral plates and corresponding to them is a series of inter- 

 mediate plates, the elevated spine bearing tabulum being wider than 

 long and covered with numerous sharp, short spinelets. The inter- 

 vals between the plates are as wide as the length of the tabulum, 

 rather deep and without papulae. External to these is a fairly reg- 

 ular series of three-lobed or T-shaped plates oriented with the arms 

 transverse to the axis of ray. The vertical portion of the T (which 

 is very short) is parallel to furrow and separates a couple of papu- 

 lae, this double series continuing to the end of ray. Adjacent to 

 these is a series of smaller, mostly crescentic, plates, oriented 

 obliquely, representing the superomarginals. Both series of mar- 

 ginals have numerous tiny spinelets similar to those of the abac- 



