Jobnson jfunb 



A NEW GENUS OF BRITTLESTARS FROAI PUERTO RICO 



By AUSTIN H. CLARK 



Curator, Dwision of Echinoderms, U.S. National Mnscnni 



(With One Plate) 



One of the most interesting of the echinoderms obtained by the 

 First Johnson-Smithsonian Deep-Sea Expedition was a curious 

 ophiuran representing a new genus of the family Hemieuryahdae. 



The family Hemieuryahdae as at present understood includes ten 

 genera, of which six occur in the West Indies. Of these six West 

 Indian genera, four are known only from the Caribbean region, 

 one is found also in other parts of the tropical Atlantic, and one is 

 represented also in the Galapagos Islands. 



The new genus may be known as — 



QUIRONIA, n. gen. 



Diagnosis. — Resembling Sigsbeia, but with a single large genital 

 slit in each interbrachial space that passes between the arm bases 

 just beyond the mouth shields ; with the arms narrower and shorter 

 and more abruptly separated from the disk, and six instead of five 

 in number ; and with the plates on the disk more numerous, smooth, 

 and less regularly arranged. 



Genotype. — Quironia johnsoni, n. sp. 



QUIRONIA JOHNSONI, n. sp. 



Locality. — Caroline station 45 ; west of Puerto Rico (lat. i8°i3'io" 

 N., long.' 67°25'3o" W.— lat. i8°i4'3o" N., long. 67°25'3o" W.) ; 

 20 to 40 fathoms; February 13, 1933. One specimen (U.S.N.M. 

 no. E.3265 [type] ) . 



Description. — The disk is 6.8 mm in diameter between the bases 

 of opposite arms, rather high, with the portion within the inner ends 

 of the radial shields flattened. The central portion of the disk is 

 covered by a considerable number of plates of very different sizes, 

 of which six, situated at the inner ends of the pairs of radial shields, 



Smithsonian Miscellaneous Collections Vol. 91. No. 13 



