172 



BULLETIN 75, UNITED STATES NATIONAL MUSEUM. 



pentagonal, but larger, and distinctly l)roader than long; they are 

 barely in contact at first (first and second finite separate) but farther 

 out become separated. Side arm plates rather large, meeting more or 

 less completely above and below, except at very base of arm; each 

 plate carries three slender, acute, subequal spines, longer than a 

 joint. Tentacle scales, none, though pores are rather large. Color 

 (dried from alcohol), disk light gray, arms nearly white. 



Localities. — Albatross station 2859, off Alaska, lat. 55° 20' N.; 

 long. 136° 20' W., 1,569 fathoms, gray ooze, bottom temperature 

 34.9°, 12 specimens; station 4761, south of Shumagin Islands, lat. 

 53° 57' 30" N.; long. 159° 31' W., 1,973 fathoms, blue clay, bottom 

 temperature 35°, 1 specimen. 



Tyi)e.— Cat. No. 25734, U.S.N.M., from station 2859. 



Although this species resembles A. lyapyracea Lyman quite closely 

 in many particulars, the much coarser disk scales and the naked inter- 

 brachial spaces serve to distinguish it easily. The specimens vary 

 little in size or details of structure. 



Fig. 77.— Amphiumna pentacantha. x 5. o, from above; 6, from below; r , side view of three 



ARM JOINTS NEAR DISK. 

 AMPHILIMNA PENTACANTHA, new species.^ 



Disk 9 mm. in diameter; arms about 70 mm. long. Disk more or 

 less swollen, covered by a coat of hundreds of small scales, many of 

 which carry minute sharp spines. Radial shields long, narrow, more 

 or less joined, somewhat sunken. Upper arm plates at first somewhat 

 tetragonal, with a long convex side distally, and angular proximally, 

 soon becoming almost perfectly elliptical, much wider than long, and 

 then gradually becoming proximally angular again; more or less 

 lightly in contact, at least basally. Interbrachial spaces below some- 

 what sparsely scaled, especially near oral shield, but with numerous 

 spinelets. Oral shields nearly circular or else a little longer than 

 broad. Adoral plates nearly horizontal and triangular, meeting 

 broadly within. Oral papilke four on a side, the apical one thick and 

 rounded, the next two elongate and pointed, the fourth very small 



a riivTs, signifying fivt\ and (kavOa, signifying spine, in reference to the five 

 arm spines. 



