GENUS — OXYNASPIS. 133 



slightly unequal in length ; the segments are broad, and 

 are paved moderately thickly with spines ; the terminal 

 spines not particularly thick. 



Caudal Appendages consist of very small and narrow 

 plates, about half the length of the pedicels of the sixth 

 cirrus, with a few long spines at their ends. 



This well-marked species, I think, has not more affinity 

 to one than to another of the previous species : it differs 

 from all, in the junction between the two segments of the 

 scuta being perfectly calcified ; in the peculiar cup, forming 

 the base of the carina ; and lastly, in the inferior part of 

 the maxillae projecting. 



Oxynaspis.* Gen. Nov. PL III. 



Valve 5, approximate i scutorum umbones in medio 

 marginis occludentis positi : carina rectangulejlexa, sursicm 

 inter terga externa, termino basali simpliciter concavo. 



Valves 5, approximate ; scuta with their umbones in 

 the middle of the occluclent margin ; carina rectangularly 

 bent, extending up between the terga, with the basal end 

 simply concave. 



Mandibles with four teeth ; maxillae notched, with the 

 lower part of edge nearly straight, prominent ; anterior 

 ramus of the second cirrus thicker than the posterior 

 ramus ; caudal appendages, uniarticulate, spinose. 



Attached to horny corallines. 



I have most unwillingly instituted this genus ; but it 

 will be seen by the following description, that the one 

 known species could not have been introduced into Lepas 

 or Paecilasma, without destroying these genera, although 

 it has a close general resemblance with both As far as the 

 valves are concerned, it is more nearly related to Lepas 

 than to Paecilasma; but taking the entire animal, its 



* From oZvvw, to sharpen, and ntm-ty, a shield or scutum. 



