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



The coxa is broad, the basis small and cylindrical ; the ischium is long and flat, 

 cylindrical at the basisal joint, and broad and flat at the meral ; the meros is long and 

 flat, straight on the inner margin and wavy on the outer, increasing in breadth from 

 the ischial joint, from whence it again narrows, and then widens at the carpal, where it 

 is armed with one small curved tooth ; indications of teeth along the posterior margin are 

 visible only under a lens ; the carpos is cylindrical and narrow where it articulates with 

 the meros, whence it increases in diameter gradually untfl it reaches the propodal 

 articulation ; the inner margin is straight and smooth, but armed with an inner and 

 outer sharp cusp near the propodal joint ; the outer margin is also straight, but not 

 parallel, being divergent ; it is grooved longitudinally, each side of the depression being 

 minutely serrate, the upper ridge terminating anteriorly in two curved sharp teeth. 

 The propodos is long, ovate, longer than the carpos, rounded on the under side, and 

 armed with a double row of very small denticles, and straight on the upper, which is 

 fringed with a number of small sharp teeth ; the polliciform process is as long as the 

 palm of the propodos ; it is straight until close to the extremity, when the point 

 suddenly thins and turns upwards ; the dactylos is straight, long, and slender ; it 

 resembles the pollex reversed, the two meeting and impinging against each other on the 

 inner margin throughout their entire length ; each of them is armed with a series of 

 closely packed, thin, obliquely and transversely placed plates, except at the long thin 

 curved points which cross and pass each other. 



The second pair of pereiopoda is short, being not more than one-third the length of 

 the first pair ; the joints are proportionately robust and less flattened ; the carpos is 

 armed at the outer anterior angle with a strong spine ; the propodos is long and 

 transversely triangular, with a ridge longitudinally traversing the outer surface, the inner 

 being flattened ; the pollex, instead of being in line with the propodos, is slightly bent 

 inwards and downwards, a direction followed by the dactylos, the inner margins of which 

 when closed, impinge against each other in their entire length, and are armed with a 

 series of minute thin plates similar to those in the first pair, but somewhat more pointed ; 

 a few long hairs planted in rows on the margins give the limb a more hirsute character 

 than the preceding. 



The third pair of pereiopoda is smaller than the second, the joints are rather more 

 slender, and the propodos is not larger in diameter than the carpos ; the pollex and 

 dactylos are long, slender, and slightly curved reversely, so that the dactylos, instead of 

 being flexed towards the pollex, is turned from it, and the pollex is curved parallel with 

 the dactylos. 



The fourth pair of pereiopoda resembles the third very closely. 



The fifth pair is still smaller and terminates in a styliform dactylos. The coxa of this 

 pair of limbs in the male (fig. 1 $ ,0,0) is large, and is perforated by a foramen, through 

 which the vas deferens protrudes. In the female the fifth pair of pereiopoda (fig. 1 0, ?) 



