OPHIUBANS OF UNITED STATES NATIONAL MUSEUM. 91 



of his paper on the Ophiurans of North America which he published in 1899. In 

 fact, he writes (99a, p. 324), "arm spines, six upper ones very slender," and a 

 little further on (p. 334), "spines nine or ten long very slender," etc. 



One can see that the examination of Ltitken's type was a necessity, and, 

 as I was fortunate enough to be able to make it, I hope that the characters of 0. pen- 

 tacrinus are now fixed. 



I have pointed out above that all the specimens of 0. pentacrinus were of 

 rather small size, and it might perhaps be thought that they represent only the 

 young form of another Ophiacantha. Now, among the forms of the Atlantic with 

 which they might be compared I see none which may be cited, except O.fraterna, 

 which shows a likeness in the arrangement of the three oral papillae which remain 

 equal and subacute. But 0. pentacrinus is plainly distinct from the latter 

 through its moniliform arms offering elongated articles and brachial spines which on 

 the upper side become very long, thin, pointed, transparent, denticulated, with 

 the rows closely approximated on the first articles. The upper brachial plates 

 are strongly bulging out and widely separated, as are also the under plates. None 

 of these characters exists in O.fraterna. 



I approximate to 0. pentacrinus, without daring, however, actually to refer 

 them to this species, three very small specimens from station 2117 (plate 9, figs. 5, 6), 

 which bear No. 12495. The diameter of the disk does not exceed 3 mm. and the 

 arms are slender and moniliform. The brachial spines and the covering of the 

 upper face of the disk show the same characters as in 0. pentacrinus, but there are 

 four oral papillae, the external one being inserted on the first under brachial plate; 

 the upper brachial plates are very small and separated by a very large space, 

 and lastly the under brachial plates, which at first were broad, become rapidly 

 longer than wide. These plates reach their maximum length between the sixth 

 and the tenth plates, then the length progressively decreases. I beg to represent 

 here a specimen in which the under plates display the maximum relative length. 



I do not see to what other species this Ophiacantha might be approximated; 

 I dare not make a new species of it, owing to the small size of the examples which are 

 probably young ones. 



OPHIACANTHA MERIDIONALIS Lyman. 



Plate 9, figs. 1-2. 



Ophiacantha mendionalis LYMAN (69), p. 324. 

 part? Ophiacantha pentacrinus LYMAN (78), p. 280. 

 part? Ophiacantha pentacrinus LYMAN (82), p. 199. 

 Ophiacantha pentacrinus KXEHLER (07), p. 319. 



Blake station 222. Feb. 16, 1879. Lat. 13 58' 37" N.; long. 61 04' 45" W.; 

 422 fathoms; s. oz.; temp. 42.5 F. 



Albatross station 2655. May 2, 1886. Lat. 27 22' N.; long. 78 07' 30" W.; 

 338 fathoms; gy. s.; temp. 47.5 F. One specimen. 



Albatross station 2664. May 4, 1886. Lat. 29 41' N.; long. 79 55' W.; 

 373 fathoms; co. s.; temp. 42.7 F. A few specimens. 



