18G PROFESSOR CHARLES CHILTON ON THE 



and the first segment of the urns bears a well-marked triangular carina. The appendages 

 are in close agreement with those of the type, and in both the inner lobe of the first 

 maxilla bears four setas instead of two as given in the diagnosis of the genus in Das 

 Tierreich Amphipoda, two of the setae being shorter than the others. 



While it is easy to identify the Scotia specimens with Mr Walker's type, the 

 position is not so clear if we try to go a little further. In the Southern Cross 

 Amphipoda Mr Walker described another species, Tiyphosa adarei, differing from 

 T. murrayi in certain minor characters which appeared at the time to be of specific 

 importance. In 1907, however, on the receipt of numerous other specimens from the 

 Discovery Expedition, he united the two species under the name T. murrayi, as the 

 examination of the specimens showed that the characters at first relied upon were 

 subject to variation. In this he was perhaps right, but a comparison of his specimens 

 of T. adarei with my specimens shows that they difier from them as they do from 

 1\ murrayi in having the first gnathopod rather stouter towards the distal end, and 

 j)articularly in having the carpus stouter and rather shorter than the propod, while in T. 

 murrayi it is as long as or longer than the propod ; though the difi'erences are not great, 

 they appear to be constant in the specimens 1 have examined. Moreover, Mr Walker 

 states that T. adarei closely resembles T. harha.tipes Stebbing, but difi'ers in the pro- 

 portions of the joints of the upper antennae and of the gnathopoda. Before comparing 

 the Scotia specimens with 2\ murrayi Walker I had also noted their great similarity 

 to T. harhatipes, except in the shape of the first gnathopods, and comparison of the three 

 shows that T. adarei is largely intermediate in this character between T. murrayi and 

 2\ hiirhatipes, so that, if the Hi\st two are united, it will be necessary to unite them both 

 with T. harhatipes. This species is, however, now placed by Stebbing in another genus, 

 Tryphosella, and the sliape of the first gnathopod in the type specimen of T. harhatipes 

 which I have also examined is considerably difterent from that of T. murrayi, the 

 carpus being shorter and the propod longer and stouter and slightly ditferent in outline, 

 as may be seen from an examination of the figure in the Challenger Eeport, and there 

 are difi'erences in some other characters. It is quite likely that an examination of 

 specimens from other localities will show complete transitional forms, but at present I 

 cannot go fully into this question, and in the meantime prefer to identify my specimens 

 with T. murrayi and to leave that species distinct from T. adarei and from T. 

 harhatipes. In all three sjDecies the side plates of the first and second gnathopoda 

 have a small tooth at the posterior angle. It is to be hoped that a complete revision of 

 this group will be made before long ; such a revision must, however, include the similar 

 forms from northern seas, some of which appear to be very closely allied. 



Tryphosa murrayi is known from South Victoria Land and from near Coats Land, 

 though not yet recorded from intermediate localities. 



(roy. soc. edin. trans., vol. xlviii., 468.) 



