OPHIURANS OF THE PHILIPPINE AND ADJACENT WATERS. 359 



The side arm plates are fairly well developed, but only slightly pro- 

 jecting; they carry on their distal border three small spines which are 

 equally spaced and. closer to the ventral than to the dorsal side. 



The tentacle pores are very large and much developed through 

 almost the whole length of the arms. The pores of the first pair-are 

 somewhat separated from the mouth slits, and they have, like the two 

 following, four or five scales on each border ; the pores of the fourth, 

 fifth, and sixth pairs have three scales on each border ; the number of 

 the scales then diminishes little by little, first on the distal border then 

 on the proximal border ; they finally are reduced to a single scale in 

 the last third of the arms. 



The color of the specimen in alcohol is white. 



Affinities and distinctive features. AmphiopMura canaliculata 

 belongs to the group of species of AmphiopJiiura in which the under 

 arm plates become longer than broad, and it recalls A . solida (Lyman) , 

 A. convexa (Lyman), etc., in the arrangement of the dorsal plates 

 of the disk. It differs from them in the form of the mouth shields, 

 and especially in the longitudinal groove which exists throughout the 

 whole length of the median ventral line of the arms and which I do 

 not know in any other species. It is exactly the opposite- arrangement 

 from that shown by Stegophiura elevata (Lyman), S. macrarthra 

 (H. L. Clark) , and S. sterea (H. L. Clark) , in which an elongated 

 prominence extends along the middle of the under arm plates. In the 

 form of the arms, which are rather slender at the base and which dc 

 not taper rapidly, this species falls well within Matsumoto's genus 

 Amphiophiura, and not in the genus Stegophiura. 



AMPHIOPHIURA FASTIGIATA. new species. 



Plate 82, figs. 1-4. 



Locality. Albatross station 5259; off northwestern Panay; Caluya 

 Island (S.) bearing S. 73 W., 19.84 kilometers (12 miles) distant 

 (lat. 11 57' 30" K, long. 121 42' 15" E.) ; 571 meters (312 fath- 

 oms) ; June 3, 1908 ; gy. M., Glob. 



One specimen (Cat. No. 41344, U.S.N.M.). 



Description. The specimen is in very good condition, but the arms 

 are all broken off at some distance from the base ; one of them is pre- 

 served for a length of 44 mm. The diameter of the disk is 16 mm. 



The disk is pentagonal and very thick The dorsal surface is plane, 

 the ventral a little convex. The arms are rounded: their sides are 

 vertical, but directed obliquely inward. The habitus of the animal is 

 very robust. 



The dorsal surface of the disk in its central region shows only a very 

 small number of plates of small diameter, while the peripheral part 

 is occupied by the radial shields, which are very large, between which 



