78 BULLETIJSr 100, UNITED STATES NATIONAL MUSEUM. 



Of the 16 lacking superomarginal spines, only the 2 largest (R=19 

 mm.) have the pedicellariae; the other 14 (with R less than 14 mm.) 

 either lack the pedicellariae, or have them in a very incipient stage. 

 The outer row of subambulacral spinelets is lacking in these small 

 specimens, otherwise the armature is very similar to that of the large 

 examples. The paxillae have 1 or 2 central and 8 to 12 peripheral 

 spinelets, relatively shorter and stouter than in the adult. The ter- 

 minal plate has 4 terminal conical spinelets. 



These small specimens differ from Astropecten granulatus in hav- 

 ing narrower superomarginals, which form a narrower border to 

 paxillar area, and distally narrower rays which taper evenly to a 

 point (not swollen) ; in having often small interbrachial supero- 

 marginal spines and large pectinate actinal interradial pedicellariae, 

 very much smaller mouth plates and a much slenderer terminal plate. 

 The inferomarginal armature is similar but the spinelets of granu- 

 latus as figured by Sladen are a little more squamiform. 



The specimens with superomarginal spines might be taken for 

 A. zehra^ but they have narrower superomarginals, smaller paxillae, 

 fewer inferomarginal spines and less squamiform spinelets, smaller 

 mouth plates and a slightly different adambulacral armature. 

 Very j'oung monacanthus has the curious chaffy inferomarginal 

 spinelets of the adult, only one marginal spine, and the very char- 

 acteristic broad spatulate subambulacral spines. It lacks, of course, 

 the superomarginal spines. 



It remains to add that one of the most striking features of this 

 species is the rapid increase in the length of ray relative to disk as 

 the animal grows. The smallest of the deep-water typical specimens 

 measures: R, 42 mm., r 7.5 mm., R=5.6 r; the next size has R, 52 

 mm.; r, 8 mm.; R=6.5 r. In the tyj)e R=7 r and in the large 

 shallow-water variety R= about 8 r. 



Type.— Cat. No. 37005, U.S.N.M. 



Type-locality. — Station 5393, between Samar and Masbate Islands, 

 Philippine Islands, 136 fathoms, hard sand. 



Distrihution. — From Masbate Island, Philippine Islands, to Sulu 

 Archipelago, the last locality somewhat doubtful. Typical form in 

 108 to 136 fathoms, sand ; varieties in shallow water. 



Specimens examined. — Typical, 4; from the type-locality, 3, and 

 1 from station 5212, between Masbate and Talajit Islands, Philip- 

 pine Islands, 108 fathoms, gray sand, mud. 



Twenty-nine small specimens from station 5182, off eastern Panay, 

 24 fathoms, fine sand and mud. At this station were taken also 

 A. velitaris and A. monacanthus. 



One large specimen, not typical, from station 5134, Sulu Archi- 

 pelago, near Basilan Island, 25 fathoms, fine sand; this locality is 

 marked doubtful. 



