*r 



THE 0PIIIURID7E. 



107 



! 



plates^ the granular covering of the disk and the three arm-spines being all 

 different. On closer examination, however, none of them are very solid. 

 The mouth papillae are not quite in accordance with Lyman's description, 

 so they had better be disregarded. As a whole they seem to have no specific 

 importance in this genus. Mouth shield and side mouth shields are very 

 different from the same parts in our figure of 0. seminudus ; but there is so 

 much variation among the specimens that there cannot be much weight 

 given to this ; thus, the side mouth-shields may have the same form as 

 those in Lyman's figure of 0. vallimola. In the mouth shield there may be 

 found a distinct character ; in 0. seminudus there is always a restriction at 

 the outer edge ; in 0. vallincola that seems not to be the case. The first 

 ventral plate is of rather different shape, but in many of our specimens its 

 form is quite indistinct. The inner dorsal plates are not rudimentary in 

 0. vallincola, but in 0. seminudus this feature is not always so prominent as 

 in the specimen figured, however always distinct. It may further be 

 remarked that the naked space is seen distinctly only in di^ied specimens. 

 The granular covering was wholly wanting in many of Lyman's specimens 



F 



of 0. vallincola ; in 0. seminudus it is only very scarce in some few specimens; 

 most of them are quite naked. 0. vallincola has three arm-spines in the 

 same place as and similar to those in 0. seminudus, which has commonly two, 

 except at the inner joints; but sometimes also the latter has three arm- 

 spines to about the middle of the arm. Finally, the outline of the disk is 

 different in the two species. The large angular plates seen along the 

 genital slits in Lyman's figure of 0. vallincola are the genital organ's, seen 

 through the skin ; the like was also seen in 0. seminudus. We think it best 

 to make a separate species of this Pacific form, as there seems not to be 

 sufficient evidence that it is identical with the Atlantic form. But certainly 

 they must be very closely related. 



|i 



6. Ophiernus annectens n. sp 



Plate V. Figs. 4-G. 



Diameter of disk, 13 mm.; width of arm close to disk, 3 mm.; length of 

 arms about seven times the diameter of the disk. Eight to ten mouth 

 papillae to each side, the three or four inner ones conical, the outer rounded 

 or square. The two at the apex mostly longer than the rest, but here much 

 variation exists : sometimes there are more short and broad papilla), quite 



t 



