1430 THE VOYAGE OF H.M.S. CHALLENGER. 



Remarks. There can, I think, be no reasonable doubt that Phrosina semilunata, 



Risso, and Phrosina nicseensis, Milne-Edwards, are the same species ; as specimens are 

 recorded an inch in length, the species evidently attains a much greater size than shown 

 by the Challenger specimens, but unless it be in the greater or les3 development of the 

 dorsal and lateral angles of some of the pleon segments, there seems to be very little 

 variation between very small and very large examples. 



Phrosina pacifica, n. sp. 



This species has so great a resemblance to that which I have already described as 

 Phrosina semilunata, Risso, that it is unnecessary to do more than note the points 

 of difference. 



The skin appears to be studded with numerous minute hairs. The An'ennas end 

 acutely, having a small linear terminal joint, the preceding large joint being apically 

 produced a little way alongside of it. 



The first joint of the First Gnathopool exhibits no dendritic markings. 



In the Second Perseopods, the finger-formed fifth joint ends acutely, without the 

 least trace of a separate finger. 



The first joint of the Third Perseopods is much expanded, so that the joint is not 

 nearly twice as long as broad, with the greatest breadth a little above the centre ; the 

 fourth joint, between the apical tooth of the hind margin and the other six acute distal 

 teeth, has a blunt tooth adjoining the hinge of the following joint. 



In the Fourth Perseopods the fourth joint has five distal teeth instead of only four, 

 besides the apical tooth of the hind margin ; the terminal finger is extremely minute, 

 scarcely distinct, except that its front margin is not quite continuous, and its somewhat 

 longer hind margin by no means continuous, with that of the fifth joint. 



The. Fifth Perseopods have a tiny triangular second joint, with blunted tip. 



The rami of the Pleopods have fifteen joints. 



The Uropocls appear in all the pairs to have microscopically pectinate edges, but this 

 may be the case also in the other species ; there are no stellate markings to break the 

 glassy clearness of the terminal portions ; the third pair are rather broader, and end 

 more squarely, though with rounded corners ; the second pair are a little broader and 

 not very much shorter than the first. 



The Telson is a little broader than Ions. 



Localities.— April 3, 1875, North Pacific, south of Japan; lat. 24° 49' N, long. 

 138 34' E. ; surface; surface temperature, 7 1°"5. One specimen. 



Station 230, April 5, 1875; North Pacific, south of Japan; lat. 26° 29' N., 

 long. 137° 57' E.; surface ; surface temperature, 68°"5. One specimen. 



