1190 THE VOYAGE OF H.M.S. CHALLENGES. 



Remarks. — The specific name is given in honour of the founder of the genus 

 Platophium. The description refers to the male, except where the contrary is expressly- 

 stated. This species bears a strong resemblance to the Australian species which Mr. 

 Haswell at first named Cyrtophium dentatum, and afterwards Dexiocerella dentata. 

 He has very kindly sent me specimens. There are not the same number of dorsal teeth 

 in the Australian as in the Kerguelen species. 



Platophium chelonise, n. sp. (PI. CXXX.). 



The lateral lobes of the head small, rounded ; the back rounded, dorsally broad at the 

 middle of the perseon ; the postero-lateral angles of the first three pleon-segments rounded ; 

 the fourth segment longer than any of the other segments, distinct from the fifth, and 

 much longer than the fifth and sixth united ; the pleon not quite so strongly flexed as in 

 Platophium danze. The skin having in many parts dark stellate markings or round spots, 

 sometimes crowded together, sometimes few and far between. 



The Eyes round, near the lateral lobes. 



Upper Antennse. — The first joint much thicker than those which follow, not much 

 longer than broad, with some slender feathered spines on the lower margin ; the second 

 joint scarcely once and a half as long as the first, with three groups of spinules on the 

 upper margin, six or seven of feathered spines on the lower, many of them long ; the 

 third joint thinner and a little shorter, similarly equipped ; the flagelham stout like 

 the peduncle, of four joints, together scarcely longer than the second of the peduncle, 

 the first not quite so long as the next two united, all carrying feathered spines, spinules, 

 and cylinders. 



Lower Antennse, not elongate, longer than the upper. The first two joints broader 

 than long, the gland-cone scarcely produced ; the third joint subequal to the first two 

 united, with a lateral distal lobe, and groups of spines upon this and on the lower margin ; 

 the fourth joint stout, longer than the preceding three united, widening distally, with 

 feathered spines at six or seven points of the lower margin, and several groups of spines 

 upon the surface and at the distal lobes ; the fifth joint rather longer, similarly armed, 

 but with the marginal spines shorter and fewer ; the flagellum of three joints, the first 

 longer than the second and third united, the three together not so long as the fourth 

 joint of the peduncle, all tipped with strong curved spines as well as slender spines and 

 spinules. 



Upper Lip — The outer plate with its distal margin rather deeply incised so as to 

 form two somewhat narrow finely furred lobes, one slightly in advance of the other. 



Mandibles. — The cutting edge divided into six teeth ; the secondary plate with four 

 small sharp teeth on the left mandible, and with a denticulate edge rather than teeth on 

 the right, this plate being as usual slighter on the right than on the left mandible, 



