OPHIUKANS OF UNITED STATES NATIONAL MUSEUM. 129 



on tho last dorsal spino which is more pointed than the others; their surface is very 

 roiio'h and it even offers very small and dense denticulations wliich are somewhat 

 unequal. The brachial spines stand perpendicular to the longitudinal axis of 

 the arm, and they do not lie at all on the lateral plates. 



The single tentacular scale is small, conical, with a blunt point; it is often 

 hidden under the first ventral spine. The examples in alcohol arc brownish-yellow. 



Connections and differences. — Owing to the arms being rolled up in a vertical 

 plane, and to their being inserted under the upper face of the disk, owing also to 

 several other characters, this species evidently belongs to the genus Oplnochondnts, 

 as it has been restricted by VerriU, and from which must be excluded 0. squamosus, 

 which forms the type of tho genus OphiocTiondrella. The new species which I have 

 just described will easily bo distinguished from the already known species by the 

 following characters: 0. convolutus Lyman possesses six spines and the disk is 

 covered with numerous granules, which are very small and dense. 0. crassispinus 

 L}Tnan also has its disk covered with very small granules, the radial shields are 

 very large, and the spines amount to seven or eight. 0. gracilis Verrill is a small 

 species, the diameter of the disk of which does not exceed 3 mm. ; the characters of 

 the upper face of the disk are unknown, but the brachial spines amount to eight. 

 Lastly 0. stelliger Lyman has its disk covered with minute granules, and the brachial 

 spines amount to four only. 



Among the Ophiurans gathered by the Princesse Alice, I described under the 

 name of Ophioplus armatus (07, p. 46, and 09, p. 203) an Opliiiiran which was 

 represented by two specimens onlj' and which I have found again among the forms 

 dred<^ed by the Albatross. After a review of that species by the examination of more 

 numerous specimens and a comparison with OpMocTiondrus granulatus, it seems to 

 me more correct to classify tliis Ophiuran also in the genus Opliiochondrus. I was 

 tempted to place it in the genus Ophioplus owing chiefly to the state of the 

 upper brachial plates, which are divided up, but it may be seen by the description of 

 0. granulatus that this character may appear also in the genus OpMochondnis. 

 Moreover, the shape of the genital slits excludes from the genus Opliioplus the 

 species from the Pnncesse Alice. Now the 0. granulatus which I have just described 

 is very closely allied with 0. armatus; I shall discuss tho differences which separate 

 these two species, after having described the specimens of 0. armatus gathered 

 by the Albatross. 



OPmOCHONDRUS ARMATUS (Koehler). 

 Plate 14, figs. 2-3, 6. 

 Ophioplus armatus Kiehier (09), p. 203, pi. 38, figs. 7, 8. 



Albatross station 2415. Apr. 1, 1885. Lat. 30° 44' N.; long. 79° 26' W. 

 440 fathoms; co. crs. s. sh. for.; temp. 45.6° F. Two specimens. 



Albatross station 2645. Apr. 9, 1886. Lat. 25° 46' 30" N.; long. 80° 02'. W 

 157 fathoms; gn. s.; temp. 43.4° F. Two specimens. 



Albatross station 2663. May 4, 1886. Lat. 29° 39' N.; long. 79° 49' W. 

 421 fathoms; br. s.; temp. 42.7° F. One specimen. 



