NARRATIVE OE THE CRUISE. 
585 
that even in the driest season (November, December, January, and February) rain falls on 
an average twelve. days in each month, the mean fall for the month being 8 inches; 
whilst in the rainy season (May, June, July, August, and September), rain falls on an 
average twenty-one days in each month, the mean fall per month being 2 7 inches. 
The northwest monsoon appears to commence about November, and lasts until .April, 
but only in January, February, and March do steady north and northwest winds prevail. 
The southeast monsoon sets in in May, and lasts until the beginning of September ; in 
the other months the winds are variable. 
During the stay at Amboina the pinnace was engaged several days in dredging in 
depths from 15 to 130 fathoms. Am ong the new species obtained were two Brachyurous 
Crabs, referred to in the following notes by Mr. Edward J. Miers, of the British Museum, 
who is preparing a Report on the Bracliyura collected by the Expedition : — 
The Brachyura. — “The Bracliyura collected during the voyage of H.M.S. Challenger 
are of much interest, not only because many of the new species are remarkable for beauty 
of form and structure, but also by reason of the additional facts relating to the distribution 
of several already described, which a study of the collection enables us to record. The 
groups richest in new genera and species are the Oxyrhyncha ( Maioidea ) .and Oxystomata 
(Leucosiidea) , and to these belong most of the new forms collected at depths exceeding 
100 fathoms. The Cyclometopa ( Cancroidea ) and Catometopa ( Grctpsoidea ) are for the 
most part terrestrial, littoral, or shallow-water species, but exceptions occur, notably in 
the genus (or rather sub-genus) Pilumnoplax, and among the swimming crabs 
(Portunidse). No Brachyurous Crab was brought up in any of the deep-water dredgings 
at depths exceeding 1000 fathoms ; at this depth a small female Crab, nearly allied to or 
identical with Ethusa microphtlialma, Smith, was dredged at the Azores (Station 73); 
and but very few were dredged at depths exceeding 400 fathoms, but between 
100 and 400 fathoms occurred nearly all the most interesting new forms in the 
collection. Sir Wyville Thomson’s statement is therefore correct as regards the 
Challenger Crustacea ‘that the Brachyurous Decapoda appear to be confined almost 
entirely to comparatively shallow water.’ 1 
“In the following brief account of the Brachyura, I have referred, as a general rule, to 
the more interesting new species in the order in which they were collected. As regards 
the pelagic species, I need only say that the Gulf Weed Crab, Nautilograpsus minutus, 
occurred not only in the north and northwest Atlantic, and at the Bermudas, West 
1 Voyage of the Challenger, The Atlantic, vol. ii. p. 349. Of. Rev. A. M. Norman, President’s Address in Trans. 
Nat. Hist. Soc. North, and Durham, vol. viii. (pt. 1) p. 42 (1883). But Prof. S. I. Smith, in a note on the Crustacea 
of the “ Albatross ” Dredgings in 1883, mentions the occurrence of a new genus of Brachyura allied to Ethusa in the 
N.W. Atlantic, in 1496 to 1735 fathoms (Amer. Journ. Sci. and Arts, vol. xxviii. p. 53, 1884 ; reprinted in Ann. and 
Mag. Nat. Hist., ser. 5, vol. xiv. p. 179, 1884). Since these notes have been in type I have received, in a consignment 
taken from among the Anomura by Mr. Henderson, some remarkable forms (probably Dorippkke) dredged at depths 
varying from 310 to 800 fathoms, and one species dredged at Station 237 in 1875 fathoms. 
