804 THE VOYAGE OF H.M.S. CHALLENGER. 



Length. — The specimen, in the position figured, measured, in a straight line from the 

 front of the head to the apex of the third uropods, one-fifth of an inch. 



Locality. — The specimen figured was taken in the Pacific, at the surface, September 

 1875. The figure of the fifth perseopods, with the adjacent ventral portion of their 

 segment, will show that this specimen was a male. A female of the same species was 

 taken at St. Vincent, Cape Verde, April 26, 1876. A third specimen, small and in poor 

 condition, was taken at the surface, lat. 24° 49' N., long. 138° 34' E. A fourth specimen 

 was taken in " W. Pacific, 16 Febr. 75." 



Remarks. — That the species belongs to Dana's genus there can be no doubt, although 

 he speaks of a single large compound eye, whereas to the present species one might be 

 justified in attributing two pairs of eyes. 



From Dana's Synopia ultramarina the present species diff"ers in having the second 

 joint of the mandibular palp much longer ; the finger of the first gnathopods in Dana's 

 species "applies against the rounded terminal margin" of the hand, which it scarcely 

 seems adapted for doing in our species ; of the first perseopods Dana says that " the 

 finger is slender, with a short claw, the whole about as long as the hand," but in our 

 species the proportions of the joints referred to are different, the hand and finger together 

 being considerably longer than the wrist. He says, moreover, that the branchise in his 

 species are oblong, sublinear, except those of the fifth perseopods. Here the epithet 

 sublinear would not apply. It is nevertheless still possible that both this and Dana's 

 own Synopia angustifvons may be synonyms of his Synopia ultramarina, the resem- 

 blances between the three having a tendency to outweigh the difi'erences. 



The figures and description given by Bovallius of his new species so closely agree 

 with those prepared for the Challenger sjjecimens, that I have little hesitation in accepting 

 his specific name, to supersede that which I had myself chosen. But here also there are 

 some slight points of diflerence : Bovallius figures a lageniform eye ; he states that in 

 the second pair of uropods the outer ramus is totally smooth along both margins, and 

 he describes the telson as " bifid with rounded ends, the fissure scarcely equalling half 

 the length of the telson," without either mentioning or figuring the small apical cavity in 

 each half of the telson. He gives the colour of his specimens as hyaline, the length 4 

 to 6 mm., the habitat "the tropical parts of the Atlantic" and "some twenty miles east 

 off Barbadoes." 



Family P o N T o P o R e 1 1 d xii, G. 0. Sars, 1882. 



Dana in 1852 established the Pontoporeinse as fifth subfamily of the Gammaridse. 

 He placed it under the heading, "Pedes 10 postici partim prehensiles," with the vague 

 and insufficient definition, "Pedes 3tii 4tique plus minusve prehensiles; 6 postici non 



