78 MR. GEOFFREY: WATKIN SMITH ON THE 



The outer ramus of uropod 3 has a minute terminal joint, and there are three groups 

 of spines, with one plumose seta. The inner ramus is small and scale-like with a single 

 terminal seta (PI. 14. tig. 24). 



The telson is cleft to the base ; the lobes are slightly concave posteriorly and carry 

 two stout spines (PI. 14. fig. 25). 



The segments of the abdomen are very spinous. 



Length 13 mm. 



Colour. Dark greenish brown. 



Occurrence. Among weed and under stones in the littoral region of the Great Lake. 



Gahmartjs antipodeus. 



The coxal plates of the fourth pair have the hind margin produced to form a triangular 

 lobe (PI. 14. fig. 21). The eyes are narrow and elongately oval. 



The first antennae have the third joint of the peduncle shorter than the second ; clothed 

 with a continuous row of short setae. The secondary appendage is of three joints 

 (PI. 14. fig. 17). 



The gnathopods are similar to those of O. ripensis, but the distal outline of the carpo- 

 podite is more sinuous (PI. 14. fig. 20). 



The pereiopods are feebly armed with very short setae ; the terminal joint with its 

 claw is stout and not long. 



The third pair of uropods project distinctly behind the other two pairs. 



The outer ramus of uropod 3 is without a terminal joint, and there are more than three 

 groups of stout spines with several plumose setae. The inner ramus is rather large and 

 has four terminal setae (PI. 14. fig. 18). 



The telson is cleft to the base ; the lobes are concave posteriorly and carry a single 

 stout spine and several small ones (PI. 14. fig. 19). 



The segments of the abdomen are quite smooth. 



Length 20 mm. 



Colour. Dark greenish brown. 



Occurrence. In Mole Creek, just after issuing from a number of large limestone caves. 

 In the caves themselves, which are quite dark, a colourless specimen was found with 

 very much reduced eyes, and more numerous plumose seta? on uropod 3. Otherwise it 

 agrees exactly with the species described. 



Gammarus australis, Sayce, Proc. Roy. Soc. Victoria, vol. xiii. (1901) p. 233, & ibid, 

 vol. xv. (1902) p. 51. 



Tins species shows more clearly than the above-described the true characteristics of 

 the genus Gammarus. Thus, besides the cleft telson and the broad internal plate of the 

 1st maxilla (PL 14. fig. 27), there are distinct sexual differences in the gnathopods, the 

 inner ramus of uropod 3 is quite long, and the secondary appendage of the first antenna 

 has six or seven joints. 



