182 ON SOME NEW AUSTRALIAN MARINE ISOPODA, 



Thoracic segments increasing slightly in breadth posteriorly. 

 Epimera of first segment not distinct ; those of second, third and 

 fourth small ; the rest larger ; those of the sixth and seventh 

 segments produced to an angle posteriorly. Greatest breadth of 

 the abdomen more than half the length ; in old specimens there 

 is a low rounded mesial dorsal ridge ; the extremity narrowing 

 suddenly and rounded in old specimens but sub-acute in younger. 

 Internal antennae very short, scarcely reaching the extremity of 

 the third -joint of the peduncle of the outer pair ; basal segment 

 of the peduncle short and thick, quadrate ; second segment shorter 

 and much narrower than the first ; third as long as the first, 

 slender, cylindrical. External antennae nearly equal in length to 

 the head and first six segments of the thorax ; three basal joints 

 short and stout, fourth the longest ; flagellum longer than the 

 peduncle, tapering, composed of about twenty articuli. Colour 

 very inconstant, sometimes olive-green, sometimes rich brown 

 variously marked with bands of dull yellow. Length of largest 

 specimen If in. 



Sab. Griffiths' Point ; Port Philip ; Tasmania. 



The nearest described ally of this species appears to be /. stricta 

 of Dana, from which it is distinguished, among other points, by 

 the much greater number of joints in the outer antennae. 



Idotea excavata, sp. nou. 



Length of body about four and a-half times the greatest 

 breadth. Head very small, much narrower than the thorax. 

 Epimera of the last six thoracic segments distinct, increasing in 

 size posteriorly — the last three acutely angulated behind. 

 Abdomen about twice as long as broad, scarcely equal in length 

 to the last four segments of the thorax, terminated posteriorly by 

 a concave border bounded on either side by an acute tooth. 

 Internal antennao short, a little longer than the three basal 

 segments of the peduncle of the outer pair : flagellum shorter 

 than the last segment of the peduncle. Outer antennte about 



