1328 THE VOYAGE OF H.M.S. CHALLENGER. 



of the outer branch ; the outer branch eight-thirtieths of an inch long, or more than 

 half the length of the peduncle excluding the inner branch ; the ornamentation is 

 similar to that in the male specimen, except that of the two pectinate margins of the 

 outer branch, both are slightly toothed ; this branch is distally a little, but conspicu- 

 ously dilated, and then rather abruptly narrowed to an acute apex ; the second pair 

 similar to the first, the branches equally long, the peduncles shorter. 



The Ventral Surface of the animal is remarkable. The description given by 

 von AVillemoes Suhm of the genital organs has been already quoted in the Note on that 

 writer (p. 438). The figure here given of the anterior part of the ventral surface of the 

 person shows at the top the central spine to which von Willemoes Suhm refers ; to the 

 rear of this, what he calls " the genital papilla " is formed by two pairs of plates, the 

 plates of each pair meeting and fitting closely together along the median line of the 

 animal ; the opening of these valves seems to be dependent upon the movement of the 

 small second pair of gnathopods, which are very stiffly connected with them ; each 

 plate has on the inner side and inner surface a lobe, of which the distal and inner 

 margins are beset with setae, and which may be supposed to correspond with the 

 marsupial plates of normal Amphipods. Behind the "genital papilla," there is a 

 transverse wrinkling of the ventral surface, and a little to the rear of this, a pair of 

 rudimentary branchiae, one of which is shown in its relative position on the Plate ; 

 behind this there is another transverse wrinkle, and again a little to the rear another 

 pair of rather larger rudimentary branchiae, one of which is also shown in its relative 

 position ; these rudimentary branchiae may be supposed to correspond to the small pairs 

 of double branchiae found attached to the second gnathopods and first peraeopods in the 

 male specimen. Only the first two joints of the second gnathopod are shown in the 

 figure of the valves, the distal part of that limb being represented in a separate figure 

 at the lower left-hand corner of the Plate. 



Length, three inches and three-tenths, or to take the measurement made when the 

 specimen was fresh, " 84 mm." 



Locality. — Station V., off the Strait of Gibraltar, January 28, 1873 ; lat. 35° 47' N, 

 long. 8° 23' W. ; depth, 1090 fathoms; bottom, Globigerina ooze; bottom temperature, 

 38°'5 ; surface temperature, 61°. One specimen, female. Trawled. 



Remarks. — For the original description of Oniscus spinosus from the Atlantic, see 

 Note on J. C. Fabricius, 1775. Fabricius makes a reference in that description to the 

 Museum Banksianum. In the cases of this museum, preserved at South Kensington, 

 no such specimen is now to be found, but among the Zoological drawings by Sydney 

 Parkinson in Capt. Cook's First Voyage 1768—1771, which form part of the Banksian 

 Museum, there are three figures undoubtedly representing a species of Cystisoma. 

 These figures are signed, " Sydney Parkinson pinxt. 1768," and bear the manuscript 



