4 RECORDS OF THE AUSTRALLA.N MTTSEUM. 



In one large and evidently old male, about J inch in length, 

 the second gnathopod was much elongated and at first sight ap- 

 peared very different. A close comparison shows however that it 

 is simply a more developed form of the gnathopod just described, 

 and that the two are not dimorphic forms. The whole limb is 

 much elongated and the set?e are fewer and much smaller in pro- 

 portion ; this loss of setpe was also noticeable in the antennte and 

 I have noticed examples in several other species which seem to 

 show that it is a change that very generally accompanies age and 

 increase of growth. 



The side-plates (epimera), (see fig. got. 2 ^ A) are small and 

 are produced anteriorly into a moderately acute process which 

 bears two or three seta? ; the basos is of the same general shape 

 as that found in the younger male but is much narrower, the 

 ischios and meros are also similar but more elongated and the setse 

 at the end of the meros are very few and small ; the carpus is 

 immensely elongated and consequently much narrower in propor- 

 tion, it is narrow towards the base and widens again distally, the 

 anterior margin is quite free from setaj except one or two very 

 small ones at the apex, the posterior margin is straight with five 

 distinct serrations, in each of which are two or three short setaj ; 

 the extremity is produced into two long processes about half as 

 long as the propodos, the process formed of the postero-distal corner 

 having the sides parallel and the end truncate, the other, corres- 

 ponding to the small rounded lobe in the younger male, with the 

 outer margin straight, inner margin slightly concave, extremity 

 rounded, quite free from set;e ; the propodos is very long and 

 narrow, the breadth not more than one-fifth the total length, the 

 whole joint is much curved inwards, the inner margin being very 

 concave and fringed with a row of scattered setaj ; the finger is 

 stouter and blunter than in the younger male and has the inner 

 margin smooth. The propodos is not movable quite in the same 

 plane as that of the carpus, but bends back on one side of it so 

 as to lie obliquely along its surface. 



I have seen only one very large male with the second gnathopoda 

 like that shown in fig. gn. 2 ^ A. Most of them were more like 

 the one represented in fig. gn. 2 ^ B, but in some the two pro- 

 cesses at the end of the carpus were a little more developed, in 

 others a little less developed than those shown in this figure. 

 Forms younger still than that represented in fig. gn. 2 ^ B would 

 no doubt approximate more closely to the female in the form of 

 second gnathopoda. 



Tlie first pereiopoda agree closely with the description given by 

 Stebbing, but I have not observed the " long transverse slit " 

 across the surface of the basos that he mentions. 



The second pereiopoda also closely resemble Stebbing's descrip- 

 tion. In both this and the preceding pair the side plates are 



