112 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



Albatross station 5629; Patiente Strait and southward; Doworra 

 Island (S.) bearing 62° W., 11.1 kilometers (6 miles) distant (lat. 

 0° 50' 00" S., long. 128° 12' 00" E.) ; 374 meters (205 fathoms) ; 

 December 2, 1909 ; co. S. 



Two specimens (Cat. 41008, U.S.N'.M.). 



Description. — In the largest specimen, which is one of those from 

 station 5629, the diameter of the disk is 9 mm.; three entire arms 

 remain attached to the disk; they are rather strongly contorted, and 

 their exact length is difficult to estimate ; they must be about 35 mm. 

 long ; these arms are rather thick, and in a general way the appear- 

 ance of the individual is rather robust. In the other specimen from 

 the same station the diameter of the disk is 8 mm. ; the arms are a 

 little more slender and a little longer, and also rather strongly rolled 

 up ; they must be about 40 mm. long. In the two other individuals 

 the diameter of the disk measures respectively 7 mm. and 4 mm. 



I shall describe the species more especially from the two specimens 

 from station 5629, of which the larger is shown in figures 1, 2 and 3 

 on pi. 27; the ventral surface of the other is shown in figure 4. I 

 also reproduce (fig. 9) a photograph of the ventral surface of the 

 specimen from station 5623, in which the shape of the mouth shields 

 is a little different. 



The disk is rounded. The dorsal surface is covered with rather 

 large plates, each one of which bears a large, very short, and thick 

 club spine, which broadens abruptly at its extremity into a large, 

 trilobed head; the width of this head may reach twice the length 

 of the cylindrical stem of the club spine (pi. 95, fig. 4). In the 

 vicinity of the periphery of the disk the heads of these club spines 

 are less developed, and often they are simply spherical. The sur- 

 face of these large heads is very rugose, and under the microscope 

 short and closely crowded asperities may be made out. This struc- 

 ture exactly recalls that which I have previously described in O. 

 mutata, to which species O. sagittata shows a rather strong resem- 

 blance in other ways. As in that species, the radial shields are small, 

 triangular with the angles rounded, and a little longer than broad; 

 the two shields of each pair are divergent and widely separated 

 throughout their whole length. Their surface is always naked, but 

 their distal border sometimes carries two or three small granules. 



The ventral surface of the disk is covered with large slightly 

 imbricated plates, almost all of which are without club spines. These 

 occur only at the periphery, in the form of small elongated granules 

 with the end rounded. The genital slits are narrow. 



The mouth shields are remarkable for their sagittate form. They 

 are almost as long as broad, or perhaps a little longer than broad ; 

 they have a sharp proximal angle, which is prolonged toward the 

 mouth, bounded by two divergent and straight sides which at. first 



