LEPAS AUSTRALIS. 91 



lateral edges of the segments on both sides, small spines ; 

 the segments in the first cirrus, and in the broad anterior 

 ramus of the second cirrus, are hemispherically and con- 

 siderably protuberant. Caudal appendages smooth. 



Size. — The largest specimen had a capitulum one inch 

 long. 



The Colours (after having been long in spirit) of the 

 valves have already been given ; sack and peduncle dirty 

 yellowish-brown, with the parts corresponding to the mar- 

 gins of the valves much darker brown, or almost black; seg- 

 ments of the cirri clouded with dark brown; body and pedi- 

 cels of the cirri dirty yellowish. I have reason to believe 

 that the colours are totally different in living specimens. 



Monstrous Varieties. — Most of the specimens from lat. 

 50° S., on the coast of Patagonia, were more or less 

 deformed, with the successive zones of growth overlapping 

 each other, and forming coarse concentric ridges. The 

 carina in several specimens was laterally distorted. 



I have already remarked that this species has some 

 affinity to L. pectinata ; but it is much more closely re- 

 lated to L. fascicularis, the affinity being clearly shown 

 by the thinness and translucency of the valves, their con- 

 vexity, by the width and little acumination of the upper 

 part of the carina, by the width of the fork, and by its not 

 being deeply imbedded. In young specimens, moreover, 

 before the fork is fully developed, there is a remarkable 

 similarity between the two species, in the form of this 

 lower part of the carina. Again, the narrowness and 

 inflection of the peduncle under the capitulum in L. cms- 

 trails, and lastly, the lateral marginal spines on both sides 

 of the segments of the posterior cirri, all clearly indicate 

 this same affinity to L. fascicularis. 



I believe this species is confined to the southern ocean ; 

 and perhaps there represents L. fascicularis of the northern 

 and tropical seas. It must, judging from the number 

 of specimens brought home by Captain Sir J. Ross, and 

 from those previously in the British Museum, and from 

 those collected by myself, be a very common species. 



