OPHIURANS OF UNITED STATES NATIONAL MUSEUM. 29 



and the differences which I noted are due very likely to a difference in the ages 

 of the specimens, VerrilTs type being larger than the one I have before me, since 

 its disk reaches 9 mm. 



In the specimen from the Blake, the upper plates of the disk are fewer; the 

 centro-dorsal plate is directly in contact with the five large radial primary 

 plates, without any intercalary plates lying between them, as stated and figured 

 by Verrill. The radial shields of each pair are contiguous on a part of their 

 length and the triangular plate which separates them distally is as long as wide 

 and may even become a little wider than long. The upper plates of the disk carry 

 fairly large granules, but these, instead of being irregularly scattered over the 

 plates, are located chiefly toward their external margin, a disposition existing 

 especially on the five radial primary plates; these arrangements give to the upper 

 face of the disk a slightly different appearance from that represented by Verrill. 

 The characters of the under face of the disk, of the mouth-pieces, and of the arms 

 being altogether in conformity with those indicated by Verrill, I thought my 

 specimen should be referred to the same species. 



OPHIOMUSIUM SERRATUM Lyman. 

 Ophiomusium serratum LYMAN (82), p. 85, pi. 2, figs. 1-3; pi. 39, fig. 10. 



Albatross station 2345. Jan. 20, 1885. Lat. 23 10' 40" N.; long. 82 20' 15" 

 W.; 184 fathoms; fne. gy. wh. co. One specimen. 



OPHIOMUSIUM TESTUDO Ljnnan. 



Plate 3, fig. 7. 



Ophiomusium testudo LYMAN (75), p. 8, pi. 1, figs. 6-8. 

 Ophiomusium testudo LYMAN (78), p. 219. 

 Ophiomusium testudo LYMAN (82), p. 99. 

 Ophiomusium testudo LYMAN (83), p. 246. 

 Ophiomusium testudo VERRILL (99), p. 14. 

 Ophiomusium testudo KCEHLER (07), p. 297. 



Albatross station 2342. Jan. 19, 1885. Lat. 23 10' 39" N.; long. 82 20' 

 21" W.; 201 fathoms; co. One specimen. 



The specimen is not altogether in conformity with Lyman's description and 

 drawings; it differs from them chiefly in having the upper plates of the disk more 

 regularly arranged and fairly equal in size. By these characters, it is closely allied 

 to two specimens kept at the Jardin des Plantes and collected by the expedi- 

 tion of the Blake. These specimens, which were given by Agassiz, were certainly 

 determined by Lyman; the diameter of the disk measures, respectively, 6 and 

 6.5 mm. ; they are consequently a little larger than Lyman's type, the diameter of the 

 disk of which was only 5.5 mm. 



In the specimen from the Albatross, the diameter of the disk reaches 7 mm.; 

 the arms are preserved to a length not exceeding 10 mm. The disk is pentagonal, 

 with rounded angles. The upper face, fairly convex, is covered with few plates, 

 the size of which is uniform. There is to be seen one large polygonal, centro- 

 dorsal plate, out of which comes a circle of small radial plates, which, moreover, 



