116 
Notes on South Australian Decapod Crustacea. 
PART 11. 
By W. H. Baker. 
[Read May 2, 1905.] 
Plates XXI. to XXIV. 
The following paper is a study of a group of Maioid crabs 
or OxyrhyncJia. The first four species and one variety belong 
to the genus Halimus, found on our coast, two of which, //. 
IcEvis, Haswell, and //. fnuicafipes, Miers, are important on 
account of their usual large size and frequency of occurrence, 
and which, as far as my knowledge goes, have never been 
figured; one, 11. tumidus, Dana, a figure of which is to be 
found in another connection, in Kongl. Svenska Vetenskaps 
Akademiens Handlingar, Band 23, Plate ii., fig. 6, a notable 
variety of this species, which I have described in detail ; and 
another which is here described for the first time. The others 
belong to different genera. 
In Professor Haswell's catalogue of Australian Crustacea 
the first three species are described ; but there are several 
points of difference which I would like to set forth which are 
scarcely mentioned by the above authors. 
The definition of the genus given by Miers in his classifi- 
cation of Maioid. Crustacea, Jnl. Lin. Soc. vol. xiv. p. 646, 
runs thus : — ''Carapace sub-triangular, with lateral marginal 
spines. Three spines above the eye. Merus joint of the outer 
maxillipeds somewhat auriculated and produced at its antero- 
external angle. Anterior legs in the male enlarged, palm 
slightly compressed. Ambulatory legs, with the penultimate 
joint more or less flattened and dilated towards its distal end. 
Type, Halimus auritus, Latreille. This genus establishes a 
transition to the Maiidse." 
In the species of this genus under consideration the 
structure of the orbital region may first attract attention as 
of importance, especially when compared with th-e corres- 
ponding parts of some members of other genera of the family 
Maiidae, with which the relationship of Halimus is undoubt- 
ed ; to mention some genera, viz., Maia, Chlorinodes, Mivtp- 
pa, Schizop/i?-i/s, Fai-annthi-ajc, and others, in which, while 
the lower margin of the orbit is usually very incomplete, 
being partially formed by the basal joint of the antenna, the 
upper is divided into, first, a short, usually thickened arcu- 
ate portion immediately above the socket of the eye peduncle, 
and posteriorly to this usually two spines — or more or less 
spiniform processes — the more posterior one of which is on a 
slightly lower level. This I take to be the true post-ocular 
