18 THE VOYAGE OF H.M.S. CHALLENC4ER. 



are numerous secondary spines on the telson between the submedian and the inter- 

 mediate, and the dactyle of the raptorial claw is armed with several teeth. In this last 

 respect, and in the flatness of the hind body, it resembles Squilla and Lysiosquilla, and 

 it also resembles all the Squillie, and diff"ers from all the Lysiosquillas in the great 

 number of secondary spines on the telson, while it resembles the Lysiosquillas and difi"ers 

 from all the Squillie except the most primitive in having the telson wider than long. 

 It resembles the most primitive species of both genera in the small size of its 

 uropods, and Claus's description renders it probable that the adult form to which it 

 gives rise has a long acutely pointed rostrum, thus differing from both Squilla and 

 Lysiosqiiilla. 



The fact that some of its characteristics are shared by the adults of both these 

 genera, while others are confined to one and still others to the other, while still others 

 are not found in either of them, indicates that its adult may be equally related to but 

 distinct from both of them. Its relation to the Lysioerichthus and Alinia larvse is of 

 precisely the same character. 



The Lysioerichthus larva probably passes through an Erichthoidina stage, with 

 retrograde metamorphosis of the third, fourth, and fifth thoracic appendages. The 

 carapace is very deep, and in the older larvae its lateral edges are folded inwards, and 

 they are serrated in the younger larv£e ; the dactyle usually bears traces of more 

 than six marginal spines, the hind body is flat and wide, the outer sj^ine of the uropod is 

 nearly always longer than the inner, the telson is mder than long, and there are from 

 one to four spines between the submedian and intermediate, and sometimes a larger 

 number in the very young laxva. 



There is no evidence that the Alima larva ever leaves the egg as an Erichthoidina. 

 The third, fourth, and fifth, as well as the three following thoracic appendages, are 

 wanting in the youngest larvae. The carajDace is shallow and flat, and its lateral edges 

 are serrated throughout the whole larval life. The dactyle bears traces of marginal spines 

 which are never more than six in number, the hind body is flat and wide, the telson 

 is longer than wide, except in Alimerichthus, and there are numerous secondary spines 

 between the submedian and the intermediate. 



In the flatness of the hind body and the presence of spines on the dactyle, Erich- 

 thcdmia resembles both Lysioet'ichthus and Alima. It resembles the very young 

 Lysioerichthus, and Alinia at all stages, in the serration of the lateral edges of the 

 carapace, while it resembles all Lysioerichthi and diS'ers from all Alimse except 

 Alimerichthus, in having the telson wider than long. It resembles all the fully grown 

 Lysioerichthi and diS'ers from all Alimw in having the carajiace very deep, with its 

 lateral edges infolded, and it differs from all Lysioerichthi and resembles all Alimse in 

 having more than four spines between the submedian and intermediate spines of the 

 telson. Lysioerichthus has the outer spine of the uropod usually longest, while the 



