OPHIURANS OF THE PHILIPPINE AND ADJACENT WATERS. 151 



(pi. 28, figs. 4, 6), and especially in that from station 5541 (pi. 29, 

 fig. 4), in which the dorsal spines at the base of the arms have a 

 length of more than six segments. I notice that these dorsal spines, 

 especially when they are very long, have denticulations less strong 

 than those on the ventral spines, but these denticulations never dis- 

 appear entirely, and I have not been able to find spines which were 

 absolutely smooth. 



It seems to me that in view of these variations it is not possible to 

 maintain the specific distinction established by H. L. Clark between 

 0. rugosa and O. polyploca, and that this latter must be united with 

 the former. 



The greater part of the alcoholic specimens are entirely white, or 

 slightly yellowish; but those from station 5520 are rather dark 

 gray. 



The Siboga met with 0. rugosa at different localities in the Sunda 

 archipelago between 5° and 10° S. latitude and 119°-132° E. longi- 

 tude, at depths varying from 204 to 520 meters (112 to 289 fathoms). 

 The Albatross collected the form described by H. L. Clark in the 

 Japanese seas between 30° and 32° N. latitude and 128°-130° E. 

 longitude at depths of from 155 to 278 meters (85 to 152 fathoms). 



Order III. GNATHOPHIURIDA. 



Family AMPHIURIDAE. 



AMPHIURA AGITATA Keehler. 



Amphiura agitata K<ehler ('04), p. 79. pi. 13, figs. 5, G, 7. — H. L. Clark 

 ('15), p. 233. 



Locality. — Albatross station 5592; Sibuko Bay, Borneo, and vi- 

 cinity; Silungan Island (M.) bearing N. 1° W., 11.86 kilometers (6.4 

 miles) distant (lat. 4° 12' 44" N., long. 118° 27' 44" E.) ; 558 meters 

 (305 fathoms) ; September 29, 1909 ; gn. M. 



One specimen (Cat. No. 41166, U.S.N.M.). 



Notes. — This specimen is a little larger than those collected by the 

 Siboga upon which I based the species; the diameter of the disk is 

 8.5 mm.; the arms are incomplete, but they taper rather rapidly 

 and their length could not have been very great. 



I notice certain differences between this specimen and the type of 

 the species ; they are correlated without doubt with the larger size of 

 the specimen. The dorsal plates of the disk are smaller and closely 

 crowded, and they do not become larger in the central region; the 

 outer mouth papilla is relatively a little less broad than in the smaller 

 specimens ; the distal lobe of the mouth shields is also a little broader, 

 and passes more gradually into the principal part of the shield ; and 



