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



Length. — The specimen, in the position figured, measured, in a straight line from the 

 front of the head to the back of the third pleon-segment, scarcely more than one-tenth of 

 an inch. 



Locality.— ^ta.tw\i 313, off Cape Virgins, Patagonia, January 20, 1876; lat. 52° 20' S., 

 lono-. (37° 39' W.; depth, 55 fathoms; bottom, sand; bottom temperature, 47°'8. The 

 specimen was obtained, with perhaps one or two more, associated with Metoj^a crenati- 

 palmata. 



Remarks. — ^This species in many respects closely resembles Metopa crenatipalmata. 

 Had the latter been the male, and the present specimen a female, the differences might 

 have been regarded as merely sexual, but the species named Metopa crenatipalmata 

 has the hand of the second gnathopod both stronger and more ornate than that found in 

 Metopa parallelochcir. 



The specific name alludes to the almost parallel sides of the hand in the second 

 gnathopods, which give it a peculiarly straight and stiff appearance that is 

 characteristic. 



Metopa ovata, n. sp. (PI. XLIV.). 



Rostrum inconspicuous, lateral lobes of the head little prominent ; the postero-lateral 

 angles of the first three pleon-segments not acutely produced, but not rounded ; the sixth 

 segment of the pleon dorsally two-edged, as is probably the case in the other species. 



Eyes round, near the front of the head. 



Up)per Antennai. — First joint longer than broad, equal in length to the second and 

 third united, the third not much shorter than the second, the flagellum longer than the 

 peduncle, of ten joints, with cylinders rather longer than the joints; the secondary 

 flagellum as usutil rudimentary, two-jointed. 



Lower Antennse scarcely so long as the upper ; first three joints very short, the first 

 a little inflated, the gland-cone small, the fourth joint about equal to the first three united, 

 broader than the fifth but not longer ; the flagellum longer than the peduncle, ten- or 

 eleven-jointed, shorter than the flagellum of the upj^er antenna. 



Upper Lip with the distal margin unsymmetrically bilobed. 



Mandibles. — The cutting edge on the left mandible obtusely angled, divided into 

 eight denticles, three small ones at the top followed by three larger in the middle, the 

 next being rather flat-topped, and the lowest acute, as large as those in the centre ; the 

 secondary plate on the left mandible not so broad as the principal plate, with a slightly 

 convex edge, cut into seven or eight denticles ; the principal plate on the right mandible 

 resembling that on the left, but with only seven denticles, the lowest but one very broad, 

 the secondary plate scarcely denticulate, but with a separate tooth at the lower end ; the 



