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



enormous foliaceous fifth joint fringed with hairs ; the terminal joints of the appendage 

 are evidently lost. 



Of the abdominal appendages I could not detect any trace. 



Station 68, off the Azores, June 24, 1873; lat. 38° 3' N., long. 39° 19' W.; depth, 

 2175 fathoms; bottom temperature, 36°"2 F. ; Globigerina ooze. 



Uyarachna, G. 0. Sars. 



Mesostmus, G. 0. Sars, Om en anormal Gruppe af Isopoden, Forhandl. Vidensk. Selsk., 1863, p. 211. 

 Uyarachna, G. 0. Sars, Christ. Fjord. Dybvands-Fauna, I860, p. 44. 



A number of very small Munnopsids dredged near Christmas Harbour, Kerguelen, in 

 120 fathoms, evidently belong to Sars's genus Uyarachna, and are the sole representatives 

 of that genus which were obtained during the voyage of the Challenger ; these specimens 

 also happen to be the only Munnopsids that were dredged in shallow water, and like the 

 shallow-water forms of the northern hemisphere are of small size. 



The definition of the genus given by Sars is as follows 1- — 



Body hardly depressed, subpyriform from above, pointed posteriorly. Anterior 

 region of body separated from posterior by a deep constriction, everywhere of approxi- 

 mately the same breadth. Head large and broad, truncated in front, with no rostrum ; 

 four anterior thoracic segments short, excavated above, with lateral processes directed 

 forwards ; three following segments large, convex above, without lateral processes ; the 

 last but one hardly narrower than anterior segments, deeply emarginate behind. 

 Abdominal segment narrow, triangular, with a pointed extremity. Upper antenna; short, 

 with a few-jointed flagellum. Mandibles short and stout, not divided at extremity, 

 furnished with an obliquely transverse crest, a narrow molar process with a few setiform 

 spines, palp absent, or small and three-jointed. First pair of legs as in Eurycope : second 

 pair differing from the rest, stouter; two following pairs subequal, and often very 

 elongate. Of the posterior thoracic limbs the first two pairs as in Eurycope; last pair 

 long and narrow, with scarcely dilated joints and a long curved terminal claw. 

 Abdominal operculum large, nearly completely covering the abdomen with a median 

 crest and numerous marginal setae. Caudal appendages simple, two-jointed ; basal joint 

 large and laminar, with plumose hairs along the margins. 



Uyarachna quadrispinosa, n. sp. (PL XII. figs. 2-6). 



Several examples of this species were dredged in shallow water (120 fathoms) off 

 Christmas Harbour, Kerguelen ; it is a very small species, the largest individual — a 

 female with eggs — only measuring 6 mm. in length. 



The head is of the same breadth as the following segments ; its antero-posterior 

 diameter is greater laterally than in the middle line ; the surface of the head is convex, 



