OPHIUROIDEA OF THE BAHAMA EXPEDITION. 33 



five-rayed variety of O. mulleri, but it was of small size and 

 agreed in all other essential characters with the ordinary, 

 small, six-rayed variety O. mulleri. At that time he gave it 

 no varietal name. 



The large specimens sent by Mr. Lyman differ from the 

 types of O. dispar only in characters of small importance due, 

 probably, to greater size. 



The arm-spines are longer and the lower ones rather less 

 differentiated from the upper ones; they are rather more 

 slender and not so much flattened and increase a little more 

 gradually in length from the lowest upward. The large 

 radial shields are semielliptical. much as in our type. The 

 upper arm-spines are regularly elliptical, and thickened. 

 The under arm-plates are, as in our types, thickened and 

 turned up at the distal and lateral margins, but many of them 

 are slightly emarginate at the outer end, becoming truncate 

 more distally. The oral shields are more rhombic, about as 

 long as broad, with a small peak or acute angle on the outer 

 end where it joins the genital scales; obtusely angled prox- 

 imally. Adoral shields not touching proximally. Mouth 

 papillae three on most of the oral margins, small, flattened, 

 the outer one (sometimes two) arises from the edge of the 

 adoral shield above the outer oral tentacle and might be called 

 an oral scale. The first oral scale is well developed, higher 

 up in the mouth-slit. 



Large clusters of minute eggs were attached around the 

 mouth and between the groups of spines near the bases of 

 the arms of our specimen. 



Diameter of disk, 11. 5 mm; length of arms, 70 mm. 



It is not probable that the specimens above described are 

 the adults of O. mulleri. They are much more like O. 

 krebsii, and may, possibly, be the adults of the latter. It 

 seems to me most probable that the specimens to which Mr. 

 Lyman first applied his varietal name in 1878 were unlike 

 those that he afterwards sent to me from another locality, 

 v— 1 c 



