New Crustacea from the Swan River Estuary. 
45 
Discussion. 
The genus Corophiurn was named by Latreille in 1806, with C. longi- 
corne as the type species. Stubbing in Das Tierreich (1906) gives excellent 
^descriptions and bibliography of the species known to him. Since his ac- 
count the number of species described has been doubled and the best modern 
account of the group is that of Crawford (1937). He divides the genus 
into three sections on the character of the urosome and the insertion of the 
uropods. He includes useful keys to the species of each group. The pre- 
sent species falls into his section B, characterised by small size, fusion of 
the urosome segments and the lateral insertion of uropods 1 and 2, in 
notches on the urosome. Crawford assigned eight species to this section. 
The female of C. minor is very like that of C. insidiosum (Crawford). 
It is however much smaller, 2-5 as compared with 4-5 mm. The relative 
lengths of the three basal segments of antenna 1 differ. Also both right and 
left dactyls of gnathopod 2 have four accessory teeth in minor whereas this 
is the case with the right only in insidiosum , the left having three. 
The male of minor differs from that of insidiosum in the structure of 
.antenna 1, and lesser features such as relative abundance of setae on various 
segments. Nor has the male of minor the very long rostrum of insidiosum. 
Like the female it is also much smaller than the other species. 
The armature of the antennae is sufficient to distinguish C. minor from 
all other species. 
Apart from the changes in armature associated with growth, normally 
occurring in this genus, two variations Avere noted. Some twenty-four females 
Avere examined. In two of these the proximal spine on the first segment of 
antenna 1, instead of being small, Avas quite large, and the second proximal 
was the smallest spine. In another specimen which did not differ from 
normal otherAvise the distal spine on segment 4 of the second antenna was 
paired (as shoA\ T n in figure) replacing in its position the more usual seta. 
Such variations in a small percentage of individuals Avas noted by CraAvford. 
It is impossible to say Avithout experimental breeding whether this is due to 
.abnormal grow T th, or to a mutation. 
LITERATURE CONSULTED FOR COROPHIUM. 
ZBarnard, K. H. : 
1915: Contributions to the Crustacean Fauna of South Africa. 5. The 
Amphipoda. Ann. S. Afr. Mus Yol. XV, Ft. Ill, pp. 105-302. 
1935: Report on some Amphipoda, Isopoda and Tanaidacea in the Indian 
Museum. Bee. Ind . Mus., Yol. XXXVII, pp. 279-319. 
1940: Contributions to the Crustacean Fauna of Sth. Africa XII. Ann 
S. Afr. Mus., Yol. XXXII., Pt. 5, pp. 381-543. 
Chilton, C.: 1921: Fauna of the Chilka Lake. Amphipoda. Mem. Ind . Miift., 
Vol. 5(, pp. 519-558. 
Della Valle, A.: 1893: F. u. FL. Neapel. Yol. 20, Gammarini, pp. 1-948. 
Crawford G I * 1937: A Review of the Amphipod Genus Coropliium. Journ. 
Mar! Biol. Assoc., Yol. XXI., No. 2, pp. 589-630. 
Hart, T. J.: 1930: Preliminary notes on the Bionomics of the Amphipod. 
Corophiurn volutator Pallas. Journ. Mar. Biol. Assoc., 1 ol. X\I, pp. 
761-789. 
