124 BULLETIN 2 01, UNITED' STATES NATIONAL MUSEUM 



Remarks. — It is somewhat difficult to decide to which genus this 

 species should be referred. It seems to be most closely allied to 

 Gibberythrops, especially in the vaulted character of the thorax, the 

 rounded anterior margin of the carapace, and the shape of the antennal 

 scale. There are, however, no plumose setae at the apex of the telson 

 and the latter is longer and more narrowly triangular and almost 

 pointed at the apex, whereas in G. acanthura the telson is shorter and 

 the apex broader and distinctly truncate. G. acanthura has only five 

 spines on the lateral margins of the telson and the long spines on the 

 truncate apex are widely separated and have a pair of plumose setae 

 between them. In the present species there are 11 to 13 spines on 

 the lateral margins of the telson, the two terminal spines are close 

 together, and there are no plumose setae. 



The mouth appendages show no very distinctive features. The 

 maxilla has a well-developed exopod and is quite normal in form. 

 The first thoracic limbs have a well-developed gnathobase on the sec- 

 ond joint but not on the third and fourth. The remaining thoracic 

 limbs are very slender in build with the propodal joint divided into 

 two subjoints. 



For the moment I refer these specimens to the genus Gibberythrops 

 and hope that the species will be recognized by the combination of 

 characters afforded by the vaulted thorax, the broadly rounded rostral 

 plate, the shape of the antennal scale, and the shape and armature 

 of the telson. 



Genus SYNERYTHROPS Hansen 



Synerythrops Hansen, 1910, p. 64. 



SYNERYTHROPS CRUCIATA, new species 



Figure 42 



Description. — Carapace produced in front into a rather long tri- 

 angular rostral plate (fig. 42, a) with a bluntly pointed apex, extend- 

 ing some little distance in front of the eyes and covering the eyestalks. 



Eyes (fig. 42, a) rather small, partially covered by the carapace, 

 with a slender fingerlike process on the inner upper surface of the eye- 

 stalk, pigment light golden brown. 



Antennal scale (fig. 42, a) four times as long as broad, outer margin 

 entire, terminating in moderately strong spine, beyond which the 

 antennal scale does not project, so there is no terminal lobe. 



Sixth somite of the abdomen twice as long as the fifth. 



Telson (fig. 42, b) half as long as the sixth somite of the abdomen, 

 equilaterally triangular in shape with a broadly rounded apex, as 

 long as broad at its base, distal quarter of each lateral margin armed 

 with eight spines, graded in size, the terminal spine equal in length 



