STARFISHES OF THE PHILIPPINE SEAS. 421 



each series decrease regularly in size toward the ambitus. In a com- 

 plete series reaching the margin at middle of interbrachium about 26 

 or 27 plates are present, while at the middle of ray about 17 or 18 

 can be counted. These plates are roundish or broadly elliptical and 

 overlap strongl3\ They bear elliptical groups of short papilliform 

 spinelets, about 10 on the small plates and 20 or 25 on the larger. 

 On the median radial areas and central portion of disk the plates 

 are of several sizes, especially at base of ray. They are small and 

 roundish or larger and crescentic or elliptical. On the distal part of 

 ray nearlj^ all the plates are small and bear a roundish group of 10 to 

 18 very short spinelets, while the larger bear 25 to 35. These groups 

 of spinelets are distinctly spaced and resemble, along with those of 

 the lateral areas, low parapaxillae or pseudopaxillae. Papulae are 

 scattered over the area of irregular plates and extend about two- 

 thirds the length of ray, but are not present on the lateral areas. 



The marginal plates are very small. The inferomarginals define 

 the ambitus, while the subequal superomarginals are abactinal in 

 position. 



The actinal intermediate areas are broad, the plates forming well- 

 marked transverse series, the plates decreasing gradually in size to- 

 w^ard the ambitus, where they are very small. In the first complete 

 series, at base of ray, are 35 plates ; at the middle of ra}'^ there are 20. 

 The larger plates bear about 15 to 20 slender, very sharp spinelets 

 about 1 mm. long and webbed into a circular group. Usually, how- 

 ever, they are bent toward the ambitus and form a double series, one 

 covered up by the other. The combs of one plate overlie the base of 

 the spines of the next plate toward the margin. Sometimes the spine- 

 lets stand more erect, and then the combs of a series do not imbricate. 

 The transverse series are separated by shallow well-marked grooves. 



Furrow spines 7 or 8 slender, untapered, blunt, united by a web 

 into a fan-shaped group wnth a strongly convex distal margm. The 

 adoral spine is usually short, about equal to base line of comb in 

 length. The next 2 are increasingly longer, the next 3, subequal, and 

 the last slightly shorter; or where there are 8 the last is nearly as 

 short as the first. Subambulacral spines proximally 18 to 20, but 

 distally only about 12. They usually stand erect, are w^ebbed, and 

 in favorable places may be seen to form a very convex series, with 

 6 or 8 spines in the concavity of the series, and involved in the same 

 membrane. Sometimes there is an appearance of 2 concentric series 

 with several irregularly disposed spines externally. 



Mouth plates with 11 or 12 marginal spines, increasing in length 

 toward the inner end of series, the companion series united by a 

 common Aveb. Suboral spines 20 to 25, in 2 series, parallel to free 

 margin, with 5 or 6 extra spines between the second series and the 



13434— Bull. 100—19 28 



