OPHIURANS OF THE PHILIPPINE AND ADJACENT WATERS. 33 

 ASTROCERAS PERGAMENA Lyman. 



Plate 93, fig. 3. 



See for bibliography : 



Astroceras pergamena Kcehleb ('04), p. 159. — Doderlein ('11), p. 61. — H. L. 

 Clark ('11), p. 284; ('15) p. 179.— Matsumoto ('17), p. 35. 



Localities. — Albatross station 5502; northern Mindanao and vicin- 

 ity; Macabalan Point Light (Mindanao) bearing S. 35° E., 15.19 

 kilometers (8.2 miles) distant (lat. 8° 37' 37" N., long. 124° 35' 00" 

 E.) ; 391 meters (214 fathoms) ; August 4, 1909. 



One specimen (Cat. No. E. 328 [part], U.S.N.M.). 



Station 5503; northern Mindanao and vicinity; Macabalan Point 

 Light bearing S. 31° E., 12.23 kilometers (6.6 miles) distant (lat. 

 8° 36' 26" N., long. 124° 36' 08") 413 meters (226 fathoms) ; August 

 4, 1909 ; gn. M. 



One specimen (Cat. No. E. 328 [part], U.S.N.M.). 



Station 5510. One specimen (Cat. No. E. 329, U.S.N.M.). 



Notes — In the specimen from station 5502, which is the best pre- 

 served, the diameter of the disk measures about 10 mm., and the arms 

 exceed 120 mm. in length. In the other the disk is a little larger, its 

 diameter reaching 11 mm. ; a single arm is entire, its length exceed- 

 ing 130 mm. ; the terminal part appears to be undergoing regenera- 

 tion. 



These two specimens, each having five equal arms, agree well with 

 Lyman's description, except in regard to the relative dimensions of 

 the disk and arms. Lyman gives for the latter a length of 100 mm. 

 in a specimen in which the diameter of the disk was 19 mm. ; thus 

 the arms are very much longer in the two Albatross specimens, in 

 which the diameter of the disk is only half as great. In both of these 

 the terminal third of the arms is extremely tenuous. 



In the proximal region of the arms the two specimens show the 

 movable dorsal spines which are characteristic of the species. In the 

 specimen from station 5503 these spines show almost the same devel- 

 opment as far as the fifteenth segment, thence diminishing rapidly 

 in size, and beyond the twentieth segment disappearing completely ; 

 in the other the spines disappear after the twelfth segment. 



In figure 3 on plate 93 are photographs of some dorsal (c) and 

 ventral (a and b) arm spines as well as the hooks which appear in the 

 terminal part of the arms (d). 



Astroceras pergamena was based upon a unique specimen found 

 by the Challenger in latitude 37° 07' N., longitude 138° 00" E., at a 

 depth of 1,033 meters (565 fathoms). 



The species was rediscovered by the Siboga in latitude 10° S., 

 longitude 123° E., at a depth of 216 meters (118 fathoms). It has 



55269— 22— Bull. 100 3 



