STARFISHES OF THE PHILIPPINE SEAS. 37 



Distribution. — Gulf of Oman and Philippine Islands 733 to 833 

 fathoms, green mud. 



Specimens examined. — Four from the following localities: 



Station 5215, east of Masbate Island, Philippine Islands, 604 

 fathoms, green mud; bottom temperature 50.5° F. ; 2 specimens. 



Station 5491, between Leyte and Mindanao, Philippine Islands, 

 736 fathoms, green mud, coral; bottom temperature, 52.3° F. ; 2 

 specimens. 



Remarks. — ^This species differs from S. psilonotus in having abac- 

 tinal spinelets, 7 instead of 5 spines on the terminal plate, and 

 usually 2 or 3 lateral mouth spines instead of 4, although the number 

 of 4 sometimes occurs. 



One of the small specimens from station 5491 has the stomach 

 full of mud. There is also a relatively large Dendrogaster parasitic 

 in the coelomic cavity. 



SIDONASTER PSILONOTUS Fisher. 



Plate 1, figs. 2, 3 ; plate 7, fig. 2. 

 Sidonaster psilonotus Fishee, 1913a, p. 600. 



Diagnosis. — Rays 5. R=22 mm.; r=ll mm.; R=2 r; breadth of 

 ray at distal edge of cribriform organ, 7 mm.; width of cribriform 

 organ 6.5 mm. : height interradially, 4 mm. Differing from S. vaneyi 

 and S. hatheri in the almost entire absence of abactinal spinelets. 

 Adambulacral spinules 2; mouth spinules, 1 unpaired and 4 mar- 

 ginal ; terminal plate with 5 spinules. 



Description. — The rays are only slightly tapered and have a 

 blunt extremity capped by a prominent spiniferous terminal plate. 

 Marginal plates forming a prominent beveled or sloping border to 

 abactinal surface. Abactinal integument on rays slightly and on 

 disks markedly sunken below upper edge of marginal plates, and 

 devoid of spinelets except for about 20 to 24, scattered close to each 

 cribriform organ, and not extending distally beyond the edge of 

 this organ. Spinelets about as long as those on surface of cribriform 

 organ. Papulae numerous, prominent, and occupying a pentagonal 

 area, the corners of which touch the middle of each cribriform organ. 

 They do not therefore extend onto the rays. There is a prominent 

 apical prolongation of the integument in center of disk, but the 

 papulae do not extend upon it. The abactinal integument contains 

 spaced, microscopic, perforated calcareous plates, roundish or irregu- 

 lar in outline, sometimes with a few short spines on the periphery. 

 These plates resemble end plates in the pedicels of holothurians, and 

 seem to consist of one layer of reticulum except that the center is 

 often slightly thickened. Madreporic body large, touching cribri- 

 13434— Bull. 100—19 4 



