REPORT ON THE CRUSTACEA MACRURA. 161 



that projects from the carapace and overlaps the anterior margin of the first somite of 

 the pleon, and another on the extremity of the somite, where it overlaps the posterior 

 margin of the carapace. 



The second somite is longer than the first, and has the anterior margin of the elevated 

 portion armed with a small anteriorly-directed tooth. 



The third and fourth somites are armed with dorsal teeth that are very large, sharp, 

 and curved forwards; the coxal plates of these and of the second somite have on the 

 surface an elevated curved line or ridge that somewhat resembles in form the outline 

 of the human ear (fig. 4), from which its specific name is derived. The anterior 

 margin of the coxal plate of the second somite is anteriorly produced to a point or cusp ; 

 posteriorly these plates diminish in size and become less round. 



The fifth somite carries no tooth, but a small carinadike ridge. The sixth somite 

 has neither ridge nor cusp, but a central depression, produced by a baccated ridge on each 

 side of the median line, the two becoming confluent at the posterior margin somewhat 

 as in Polycheles euthrix, Pobjcheles hclleri, and Pohjcheles baccata. The telson has two 

 small cusps in the median line. 



The orbital notch (fig. 3C) has the inner and outer margins nearly parallel, and the 

 ophthalmopod is armed on the anterior margin with an obtuse cusp ; the lateral portion 

 passes outwards beneath the anterodateral projection of the carapace. 



The first pair of antennae has the scpiamiform process smooth on the inner margin 

 and produced anteriorly to a sharp point ; the outer margin near the anterior angle is 

 armed with two sharp teeth, one before, the other behind the fissure that opens into the 

 auditory chamber ; the second joint is long, the third short and terminating in two 

 unecpial flagella, of which the inner is rather more than half the length of the carapace 

 and the other is very slender and of about the same length as the peduncle. 



The second pair of antennas (fig. 3c, c) carries a long phymacerite that turns 

 inwards and upwards, with its extremity lying in a depression in the under surface 

 of the first joint of the first antennas. The scaphocerite is slender and obtusely 

 pointed. 



The oral appendages have not been disturbed, but, so far as observation could be 

 made, there is no reason to suppose any variation from the common character. 



The second pair of gnathopoda supports a rudimentary mastigobranchia, but otherwise 

 does not vary much from the common type. 



The first pair of pereiopoda is delicate and generally free from armature, excepting 

 one small tooth on the outer margin of the meros, at a little distance from the basisal 

 articulation, another near the external distal angle of the same, and one on the inner 

 and one on the outer angle of the propodal extremity of the carpos. 



The other pairs of pereiopoda have the common typical form, except in the chelate 

 character of the posterior pair. This appendage is shorter than the preceding, and 



(ZOOL. CHALL. EXP. — PART LII. 1886,) Fff 21 



