232 
HORN EXPEDITION—CRUSTACEA. 
Lower surface of telson minutely spinulose, witli a median and two lateral 
depressions, free or nearly free from spines. 
Caudal appendages considerably longer than the median length of the 
carapace. 
Second antenme absent. 
The fifth endite of the first thoracic appendage varying much in length. It 
may reach as far back as the fifteenth exposed abdominal segment, or it may reach 
only to the posterior end of the carina. 
No diffei’ence in size or proportions between the males and females. 
Colon?'. - The carapace is light yellow, with dark brown along the carina and 
the margin ; the transverse ridge behind the eye is outlined in brown. The 
eyes are dark, with a red margin. The tail is light yellow, with at times a 
greenish tinge, and the spines stand out as dark brown, with a small circle of 
yellow-brown around their bases. When alive the gill-plates are prominent, owing 
to the presence of red blood in them. In spirit the carapace darkens somewhat. 
Total length of the largest male, from the anterior margin of the carapace to 
the end of the telson, 70 mm. 
Total length of the largest female, 64 mm. 
Out of a total of fifty-eight individuals, six are males, fifty-two females. 
This is the only species of Apus as yet described from Australia. We are 
indebted to Mr. J. J. Fletcher for calling our attention to two brief notices which 
have already been published indicating that specimens belonging to this genus 
have previously been observed though not described. 
]\lr. Sangster* mentioned that one was to be found in watei’-pools after rain 
in Central Australia. This is in all likelihood the one which we describe, though, 
as Mr. Sangster has given no description, we are unable to state definitely what 
species he found. 
Mr. Tryonf notes that Dr. Bancroft brought back a specimen from Wompah, 
in the south-west corner of Queensland, but as the specimen is not named or 
described, we are unable again to say whether ours is or is not identical with the 
Central Australian form. 
* We are indebted to Mr. Fletcher for a copy of this paper, published in the Ain. Naturalist, xviii., 1884, p. !>. 
t Nat. Hist. Soc. Queensland, vol. i., p. C4. 
