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



series of ciliated hairs that are generally worn off, excepting where the projecting tooth 

 protects it. The lower margin is furnished with two teeth which are situated near 

 the middle, between the orbit and the apex of the rostrum, and the whole edge is 

 fringed with small hairs. The orbit is defined at the outer canthus by a prominent 

 rounded lobe, beyond which stands a conspicuous antennal tooth, and behind and 

 beneath it a conspicuous hepatic tooth. The fronto-lateral angle is rounded and un- 

 armed. 



The pleon is dorsally rounded and laterally compressed. The third somite is not 

 longer than the second and is not arcuate, and the sixth somite is but a little longer than 

 the fifth. 



The ophthalmopoda stand upon a short pedicle ; the ophthalmus is hemispherical, 

 and has a small ocellus beyond the margin. 



The first pair of antennas is nearly as long as the second, and two-thirds the length of 

 the animal ; the first joint is excavate to receive the ophthalmopod, and has the margin 

 fringed with hairs, those on the anterior wall of the excavation being directed posteriorly ; 

 the stylocerite is short, and so closely impacted against the margin of the joint that it 

 ceases to be an offensive weapon ; the outer distal angle is armed with a strong but 

 short tooth ; the second and third joints are subcylindrical, and articulate with each 

 other obliquely, the inner distal angle of the second joint being produced on the under 

 surface nearly to the extremity of the third joint. The outer flagellum is stout at the 

 base and soon sends off a secondary branch that is slender, and as long as the inner 

 flagellum. 



The second pair of antennae is longer than the animal and supports a large 

 scaphocerite that reaches to the extremity of the rostrum, it is armed on the outer side 

 with a tooth that is closely impacted into the margin, and does not reach to the 

 extremity of the appendage. The base of the peduncle is armed on the outer and lower 

 angle with a strong tooth, above which is a lobe, and between this aud the tooth there is 

 a groove into which the scaphocerite falls when projected backwards. 



The oral appendages correspond with those of Palsemon serratus. 



The first pair of gnathopoda closely resembles that of Paliemon. 



The second pair terminates in a sharp unguis and has the sides thickly furred with 

 short, stiff hairs, and the coxa bears a short and broad calcified process. 



The first pair of pereiopoda is slender, and when extended reaches considerably beyond 

 the apex of the rostrum ; it is chelate, the pollex and dactylos being nearly as long as the 

 palm of the propodos and impinging in their entire length, and furnished with numerous 

 fasciculi of hair ; the propodos is narrow, not broader than the carpos, and about half 

 its length ; the carpos is long, narrow, and cylindrical ; the meros is three-fourths the 

 length of the carpos, cylindrical, and slightly more robust ; the ischium is short, about 

 half the length of the meros, and on the inner side for nearly the entire length of the joint 



