276 Miss H. Richardson on the Isopods of the 



to tlie end of the second joint of the second pair of antennae. 

 The first joint of the second pair of antennae is visible and 

 unarmed ; the second joint is armed with three spines ; the 

 tliiid joint is unarmed and is about twice as long aa the 

 second joint ; the fourth and fifth joints are about equal in 

 length and are each about twice as long as the third ; the 

 flagellum contains three joints. 



Fig. 28. 





Arcturus intermedius. X 10. 



The first, second, and third thoracic segments have a trans- 

 verse row of six large spines, three on either side of the 

 median longitudinal line, the two centre ones being the 

 longest, although all are very long. The fourth segment is 

 twice as long as any of the other segments and has a trans- 

 verse constriction on the posterior half of the segment. On 

 the anterior portion are six spines, three on either side of the 

 median line, the four outer ones being in a straight line, the 

 inner two below this line. On the posterior portion are six 

 spines also, three on either side of the median line. The 

 fiith thoracic segment has twelve spines, six on either side of 

 the median line. The sixth segment has ten spines, five on 

 either side. The seventh and last segment has eight spines, 

 four on either side. 



