18 
THE VOYAGE OF H.M.S. CHALLENGER. 
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 Squillse, and differs from all the Lysiosquillse in the great 
number of secondary spines on the telson, while it resembles the Lysiosquillse and differs 
from all the Squillse 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 
Lysiosquilla. 
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 Alima larvae is of 
precisely the same character. 
The Lysioerichthus larva probably passes through an Ericlithoidina 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 larvae ; the dactyle usually bears traces of more 
than six marginal spines, the hind body is flat and wide, the outer spine of the uropod is 
nearly always longer than the inner, the telson is wider than long, and there are from 
one to four spines between the submedian and intermediate, and sometimes a larger 
number in the very young larva. 
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 larvse. The carapace 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- 
thalmia resembles both Lysioerichthus and Alima. It resembles the very young 
Lysioerichthus, and Alima at all stages, in the serration of the lateral edges of the 
carapace, while it resembles all Lysioerichthi and differs from all Alimas except 
Alimerichthus, in having the telson wider than long. It resembles all the fully grown 
Lysioerichthi and differs from all Alimas in having the carapace 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 
