34 ALLAN HANCOCK ATLANTIC EXPEDITION REPORT 



Abdomen flattened, loosely articulated, without carinae or spines ex- 

 cept at posterolateral angles of sixth somite. 



Telson smooth dorsally, much broader than long, posterior margin 

 forming a false eave over true posterior spines ; false eave with rounded 

 median projection, flanked by a deep concavity on either side; lateral 

 spines and apices of submedian denticles visible dorsally; submarginal 

 armature, on either side, consisting of a row of 11 submedian denticles, 

 increasing in size laterally, a movable submedian spine, anterior to 

 outermost denticles, and a curved row of five fixed spines lateral to the 

 outermost denticle; second and fourth fixed spine smaller than the re- 

 mainder. 



Uropodal outer branch with 5 graded, movable, spatulate spines on 

 outer margin of penultimate segment, last spine extending past mid- 

 point of ultimate segment ; inner distal margin of penultimate segment 

 of outer branch with two slender, movable spines; inner spine of basal 

 prolongation much the longer. 



Discussion: L. hancocki is closely related to L. grayi Chace, from 

 which it can be separated by the rectangular anterolateral angles of 

 the rostral plate, the small number of teeth on the raptorial claw (10 

 on L. hancocki, 11-15 on L. grayi), and the spination and sculpture of 

 the telson. In L. hancocki there are 22 submedian denticles, as opposed 

 to 15-18 in L. grayi) the movable submedian spines are anterior to the 

 outermost denticle, not adjacent to it as in L. grayi, and the depressions 

 on either side of the false eave are deeper and more angulated laterally 

 than in L. grayi. 



L. hancocki is also related to L. decemspinosa Rathbun and L. 

 chilensis Dahl from the eastern Pacific. It differs from both in having 

 a deep concavity lateral to the median projection of the false eave of 

 the telson ; also, L. chilensis has many more spines on the raptorial 

 dactylus, 12-17, the rostral plate is rounded anterolaterally, and the two 

 spines of the basal prolongation are subequal. L. hancocki differs from 

 L. decemspinosa chiefly in the shape of the false eave and in the ar- 

 rangement of the denticles and teeth of the telson. 



The species is named for Captain Allan Hancock, in recognition of 

 his support of the marine sciences. 



Remarks: Upon first examination, I felt that this specimen would be 

 referred to L. decemspinosa, a species known only from the eastern Pa- 

 cific. Direct comparison with the type and other available material of 



