238 COLLECTIONS FKOil MELANESIA. 



than its greatest vertical depth, which is at the articulation with 

 the mobile finger, smooth and polished externally, its upper margin 

 not carinated, its inner surface with a dense patch of hair ; the 

 lower margin of the immobile finger is in a straight line with the 

 lower margin of the palm, its upper or inner margin is denticulated 

 and has a strong tooth or lobe in the middle ; the inner margin of 

 the mobile finger has a smaller tooth near its base ; the fingers, 

 when closed, meet only toward their apices, having an hiatus be- 

 tween them, which is hollowed out into a deep, nearly semicircular 

 cavity at the base of the immobile finger ; this cavity is margined 

 with hairs. The ambulatory legs are slender, somewhat compressed, 

 and the margins somewhat thinly clothed with hair. Colour, in 

 spirit, brownish. Length of carapace nearly 3 lines (6 millim.), 

 breadth 3| lines (somewhat over 7 millim.) ; length of chelipede 

 about $>h lines (over 11 millim.). 



The single specimen (a male) was obtained at Port Jackson, 

 5-7 fms. (No. 104). 



In the relatively narrow and quadrate carapace this species may 

 be compared to such forms as Macrophthalmus pacificus, Dana*, 

 to which species apparently belong specimens recently received from 

 Timor Laut (//. 0. Forbes), Macrophthalmus bicarinatus, Heller f, 

 and M. quadratus, A. Milne-Edwards j. 



M. pacificus and M. bicarinatus differ in their narrower front, 

 &c. ; M. quadratus has but two lateral marginal teeth, and no lobe 

 or tooth on the inner margin of the immobile finger. Macroph- 

 thalmus setosus, an Australian species very briefly characterized by 

 Milne- Edwards §, has, I suppose, a wider carapace. Specimens 

 provisionally referred to this species in the British-Museum collec- 

 tion are certainly very distinct from our new species. 



Macrophthalmus latifrons, Haswell |], from Port Phillip, has the 

 carapace finely granulated, the immobile finger of the chelipedes 

 defiexed, &c. 



In many of its characters our species approaches Euplax (CJiazno- 

 stoma) boscii and E. crassirnanus, Stimpson, in both of which there 

 are but two teeth on the lateral margins of the carapace. In 

 Hemiplax hirtipes, Heller, not to mention other distinctions, the 

 fingers are only minutely denticulated on their inner margins. In 

 the absence of catalogues or systematic lists of the species, it is with 

 great hesitation that I venture to describe this as a new form among 

 so many nearly allied species. 



83. Euplax (Chaenostonia) boscii (Audouin). 



A small male is in the collection from Port Molle (Xo. 9.")). 

 This example in its coloration and all other characteristics coin- 



* U.S. Exploring Expedition, Crust, xiii. p. .*514, pi. xix. fig. 4 (1852). 



t Eeise der Novara, Crust, p. 36, pi. iv. fig. 2 (1865). 



J Nouv. Archiv. Mas. Hist. Nat. is. p. 280, pi. xii. fig. 6(1873). 



§ Ann. Sri. Nat. s6r. 3, Zool. xviii. p. 159 ( 1852). 



\ Catalogue, p. 90 (1882). 



