242 ATJSTBALIA1T MAIACOSTBACA. 



the seventh and the first three segments of the pleon very wide ; 

 the seventh segment of the pereion and the first three segments 

 of the pleori each armed with an acute spine on each side near 

 the middle dorsal line, and another at the postero-lateral angle ; 

 third segment armed in addition with an acute, curved spine, 

 situated between the lateral angle and the dorsal spine. Coxs 

 of the gnathopoda and the two anterior pairs of pereiopoda deep, 

 that of the second pair of pereiopoda excavated behind for that 

 of the third pair, the latter, together with the two following pairs, 

 with a spine-like posterior angle. Antennae subequal, the inferior 

 pair rather longer than the superior. Anterior gnathopoda 

 slender, filiform. Posterior gnathopoda slender, subchelate. 

 Basos of the third pair of pereiopoda armed on the posterior 

 border with an acute spine near the proximal end ; basos of the 

 fourth pair with two short spines, that of the fifth pair with the 

 posterior border serrate and armed with an acute spine near its 

 distal extremity. Last pair of pleopoda biramous, the inner 

 ramus longer than the outer, bi-articulate. Telson scale-like, 

 entire. Colour red with brown dots. Length ■$% in. 



Port Jackson (dredged,). 



Sub-Family Gammarides. 



Usually laterally compressed. Eyes two, compound, situated 

 upon a protuberance between the superior and inferior pairs of 

 antennse. Antennae situated one above the other. Superior 

 antennse long, slender and filamentous. Inferior antenna? sub- 

 equal with the superior. Pirst pair of gnathopoda more or less 

 subchelate; second also, and generally well developed. The 

 posterior pleopoda never furnished with hooks. Telson squami- 

 form or tubular. [& £.] 



Genus Atylus, Leach. 



Animal compressed. Antenna? subequal ; superior without a 

 secondary appendage. Maxillipedes unguiculate, having a 

 squamiform plate developed from the basos and ischium. 

 Gnathopoda subchelate. Pereiopoda subequal. Posterior pleo- 

 poda biramous. Telson single, squamiform, divided. [_S. B.] 



