260 



Smithsonian Institution. 



Cape St. Lucas, Lower Cal. J. Xantus. 



OpJdonereis porrecta, (Lyman,) sp. nov. 



Description of a Speciynen. Diameter of disc, 12 millim. 

 Width of arm, without spines, 2.5 millim. Length of arm, 113 

 millim. Mouth-papillffi 10, short, stout; the outermost but one 

 broadest. Teeth 4 or 5, stout, squarish, rather long, a little taper- 

 ing, lowest one shortest. Mouth-shields oval ; length to breadth, 

 1.6:1. Side mouth-shields very small, triangular; sometimes 

 almost obliterated. Under arm -plates squarish, broader without 

 than within ; outer side curved, inner side nearly straight, lateral 

 sides reenteringly curved ; length to breadth, (20th plate,) 1 : 1.2. 

 Upper arm-plates varying in proportionate breadth, according to 

 the width of the arm ; usually broader than long ; inner side 

 much longer than the outer ; outer and lateral sides often con- 

 founded in a common curve ; length to breadth, (35th plate,) 

 1 : 1.6. Scales of disc rather stouter than usual in the genus ; 

 about 80 to a square millim. Radial shields, 1.2 millim. long. 

 Scales on edge of disc larger than the rest. Papillae along edges 

 of genital slits stout and prominent. Arm-spines 3, short, rounded, 

 tapering ; lengths to that of under- arm-plate, (23d joint,) 1, 1.7, 

 1.3 : 1. Tentacle-scale 1, oval, large. Color, in alcohol : above, 

 disc minutely mottled and lined with dull reddish brown and dirty 

 white ; arms the same, but darker, with here and there a lighter 

 joint ; arm-spines pale brown, with one or two darker rings ; be- 

 low, interbrachial spaces tawny brown ; mouth-parts and under 

 arm-plates white, with specks of several tints of brownish. 



Variations. A young one, with a disc of 3 millim., had arms 

 18 millim. long. The disc-scales were large; about 40 to a 

 square millim. ; and, among them, the primary plates could 

 plainly be seen ; the radial shields were conspicuous, though 

 small, and were separated by a wedge of two or three scales ; the 

 upper arm-plates were nearly circular, and overlapped each 

 other ; the under arm-plates were shield shaped, having an angle 

 wdthin, and a wide, straight, outer side, and were entirely sepa- 

 rated by the encroachment of the side arm-plates. The colora- 

 tion varies chiefly in intensity. 



The locality of these specimens has unfortunately been lost ; 



