CYMODOCEA. 425 



ISOPODA . SPIUSROMIDJE. 



NORM ALIA. 



Genus CYMODOCEA. (Leach.) 



Generic character. Not capable of being completely rolled 

 into a ball. Pleon very rugose, deeply excavated at the tip, 

 with a lobe or tooth in the middle. Uropoda with the plates 

 elevated obliquely, so as not to shut under each other, the 

 inner plate being a process of the peduncle. 



THESE species are easily distinguished by the very 

 rugose and setose segments of the tail, which is terminated 

 by a deep notch, within which is a produced central plate 

 or lobe. The body is more parallel at the sides than in 

 Sphceroma, all the segments being simple. These charac- 

 ters will at once distinguish the genus both from Sphceroma 

 and Dynamene, which latter has been united with it as a 

 second section by Professor Milne Edwards. 



The head is nearly as broad as the broadest part of the 

 body. The flagella of both pairs of antennae are multi- 

 articulate. The penultimate segment of the tail (forming 

 the posterior margin of the consolidated basal mass) is 

 prolonged in the middle and emarginate, the terminal 

 segment bearing in the centre of its upper surface a com- 

 pound tooth or spine, and the extremity of the tail is 

 deeply notched, with a short horn or lobe in the middle 

 of the notch. The foot-jaws have the intermediate joints 

 prolonged on the inner margin, the extremity of the lobes 

 thus formed being thickly ciliated. The lateral appen- 

 dages of the tail have two small lobes, which are strongly 

 ciliated with stiff short hairs, which also are thickly 

 scattered upon the upper surface of the segments of the 

 tail. 



