34! EEV. T. E. E. STEBBING — BISCATAN PLANKTOX : 



the length as varying from 4 to 6 mm. But the original Lestrigonus Fahr'ei of Milne- 

 Edwards is said to be " long d'environ cinq lignes," equivalent to 10"5 mm. From the state 

 of knowledge at the time wiien Milne-Edwards was writing, it was scarcely to be expected 

 that either his description or figure would contribute much of the detail now required 

 for discriminating species of this genus, but the disparity of size is so great as to make 

 the identification of his form from the Indian Ocean with that since found in the 

 Atlantic, to say the least, highly improbable. I therefore propose to distinguish the 

 H. Fabrei of Bovallius by the new name Eyperia Vosseleri. 



In S. hizoni, according to Vosseler, the fifth joint in the first pereeopods is armed 

 with a single stifily outstanding seta, in the second pair with two such setae, and in 

 each of the three following pairs with one slender seta. My own observation agrees 

 wdth this account, except that I find two of the setae or spines on the fifth joint in 

 the first as well as in the second perseopods. They are found also in both first and 

 second peraeopods of S. Vosseleri. In that species the spine is wanting on the fifth 

 joint of the last three pairs of peraeopods. But also in the ' Challenger ' specimens of 

 H. luzoni this spine was wanting. 



Occurrence: Z^d. 100 to fathoms. 1 ovigerous ?. 



Hyperigides, Ohevreux, 1900. 



1900. Hyperioides, Chevreux, Ampliipodes de PHirondello, p. 143. 



1901. Parahyperia, Vosseler, Amphipoden der Plankton-Expedition, p. 56 (without definition). 



M. Chevreux gives the following definition of the genvis : — " Body much more com- 

 pressed tlian in the species of the genus Hyperia. Head prolonged anteriorly, above 

 the insertion of the upper antennae. Eyes occupying only the upper part of the head. 

 Palp of the mandibles remarkably long. Basal part of the maxillipeds very elongate ; 

 internal lobe little developed. Carpus [fifth joint] of the gnathopods strongly produced 

 in both pairs. Eeet of the fifth and sixth jxiirs [third and fourth peraeopods] very 

 long, equal ; feet of the seventh pair [fiftli peraeopods] much shorter. Uropods rather 

 elongate. Telson much broader than long, semicircular." 



The definition, as it stands, applies to a single species and in fact to only one sex of 

 that species. Here, as in some other members of the Hyperiidae, it proves that the 

 female is devoid of a mandibular palp. But there are probably two species already 

 known, which are so closely allied that the generic character must be further modified 

 so as to admit them side by side. Dr. Vosseler, while studying the same form as 

 that which M. Chevreux has named Hyperioides longipes, was so struck by its resem- 

 blance to the ' Challenger ' species Hyperia sibaginis that he described it under that name. 

 Unaware at the time of M. Chevreux's recently published generic title, he suggested 

 in his own work the designation Farahyperia as suitable for marking the rather fine 

 distinctions by which the new genus is separated from Syperia. Also he suggested 

 that the European form might have to be called Eyperia sibaginis var. longipes or simply 

 Hyperia longipes, thus not insisting on his proposal of a new genus Tarahyperia, but 

 lighting upon the very same specific name as that already used by M. Chevreux. 



.A 



