1214 THE VOYAGE OF H.M.S. CHALLENGER. 



Remarks. — The young specimen is the subject of PL CXXXV.; its length, from the 

 rostrum to the extremity of the second segment of the pleon, is less than one-tenth of 

 an inch ; the figures will, I think, sufficiently show, without a detailed description, that 

 the differences between the smaller and larger specimens are only such as might be 

 expected between a very young specimen and an adult ; in the young the spines are 

 fewer on the palp of the first maxillse, on the maxillipeds, gnathopods, uropods, &c; 

 the telson is much shorter in proportion to its length ; the pleopods have a single cleft 

 spine, and only four or five joints to the rami ; the third uropods are not lanceolate. 

 The latter difference recalls the still more remarkable divergence between the third 

 uropods of the young and of the adult in Amathilla homari (Fabr.), better known as 

 Amathilla sabini (Leach), a divergence which was pointed out by Bruzelius in the Skand. 

 Amph. Gamm., p. 51, 1859, and further noticed by Buchholz, in Die zweite deutsche 

 Nordpolarfakrt, in 1874. 



The specific name refers to the peculiar hind margin of the first joint in the third 

 and following perseopods. It is a curious coincidence that, after the capture of a single 

 specimen of the young of this new species at one station, at the very next station, but 

 much more than a hundred miles away, a single specimen of the adult should have been 

 obtained. The two large specimens of Andania gigantea from far greater depths present 

 a similar coincidence that is even more striking. 



Family Helaida 



In 1872 Boeck named the Helainse as second subfamily of the Corophiidse, and in 

 1876 defined it as follows : — 



" Mandibles with the third joint of the palp shorter than the second. 



" Maxillipeds with the outer plate armed on the inner margin with few but strong 

 teeth. 



"The body slender, depressed ; the side-plates tolerably small. 



" Antennse? 1 



" Legs rather elongate ; First Gnathopods larger than the Second. 



" Last three pairs of Perseopods graduated in length, the hinder the longer ; the first 

 joint not dilated, linear ; the fourth joint very small. 



" First and Second Uropods biramous, the Third uniramous." 



This definition Boeck had given in 1870 as that of the genus Hela, and in his later 

 work, the definition of the subfamily is allowed to stand for the character of the single 

 genus contained under it. Sars in 1882 relinquishes the subfamily Helainse altogether, 

 including its one genus under the family Corophiidse. 



1 Both pairs very long ; upper with secondary flagellum, see Hansen, loc. cit. 



