116 BULLETIN 84, UNITED STATES NATIONAL MUSEUM. 



truncated, but becomes sharper and sharper, slightly diverging lateral sides, which 

 are excavated by the large tentacular pores, and a wde and convex distal side. 

 They remain contiguous on almost the whole length of the arms, owing to their 

 proximal angle becoming elongated, but they finally get separated. 



The lateral plates bear three fairly wide spines which are flattened, with an 

 obtuse point and a rough surface; these spines are equal, and their length is equal 

 to that of the article; the ventral spine is flattened and a httle wider than the 

 others. 



The fairly large and oval tentacular pores are each provided with a httle 

 lanceolate scale. 



Connections and differences. — This species really belongs to the genus OpTiiologi- 

 mus, which was introduced by II. L. Clark in 191 1 for an ojihiuran, 0. hexactis, which 

 also has six arms; the single specimen had been gathered at Suno Saki (Honshu 

 Island, Japan), between 83 and 158 fathoms. The Atlantic species is evidently 

 very closely alUed to 0. hexactis, but it is plainly separated from it by the presence 

 of very distinct radial shields, by the upper face of the disk being covered with 

 scales aU over, even in the younger examples, by the dorsal plates of the disk, which 

 extend but very httle over the bases of the arms, by the upper brachial plates, which 

 are triangular and as long as wide, and finally by the presence of a single tentacular 

 scale. 



H. L. Clark introduced in the diagnosis of the genus Ophiologimus the absence 

 of radial shields; therefore, this character ought to be corrected, since these 

 shields exist in the new species. 



The discovery in the Atlantic of a second species of the genus OpMologimiis is 

 very interesting. 



OPHIOCHITON GRANDIS Verrill. 

 Ophiochiton grandis Verrill (84), p. 384. 

 Albatross station 2394. Mar. 13, 1885. Lat. 28° 38' 30" N. ; long. 87° 02' W. ; 

 420 fathoms; gn. m.; temp. 41.8° F. One specimen. 



Albatross station 2395. Mar. 13, 1885. Lat. 28° 36' 15" N. ; long. 86° 50' W. ; 

 347 fathoms; gy. m.; temp. 44.1° F. One specimen. 



Family OPHIOCOMID.^. 



OPmOCOMA ALEXANDRI Lyman. 



Ophiocoma alexandri Lyman (65), p. 74. 

 Ophiocoma alexandri Ljungman (66), p. 329. 

 Ophiocoma alexandri Verrill (67), p. 259. 

 Ophiocoma alexandri Ives (89), p. 177. 

 Ophiocoma alexandri Kcehi,er (07), p. 325. 



Albatross station 2824. Apr. 30, 1888. Lat. 24° 11' 30" N.; long. 109° 55' W.; 

 10 fathoms; brk. sh. One specimen. 



Diameter of the disk, 8 mm.; length of arms, 55-58 mm. 



The sample is of a hght brown and rather uniform color; despite its small size 

 it is plainly characterized. The tentacular scales are two in number on the pores 

 of the three and sometimes four first articles. 



