KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 22. N:0 7. 



277 



Themfsto, F.E.GUERIN. G. M. Thomson. 



C. Claus. 



Euthemisto, » 



» 



1880. 



A. Gerstaecker. 



1886. 



C. BOVALLIUS. 



1887. 



H. J. Hansen. 



Th. Stebbing. 



1879. "New Zealand Crustacean. Trans, and 



Proc. of the New Zealand Institute. 



Vol. 11, p. 242. 

 1879. »Der Organismus der Phronimiden». Arb. 



Zool. Inst, der Universitat Wien. Tom. 



2, p. 602 (2). 

 Grundziige der Zoologie. 4:te Aufl., 



l:ster Band, p. 587. 

 Dr. H. G. Bronn's Klassen uud Ord- 



nungen des Thier-Reichs. Bd. 5. Abth. 



2, p. 491. 

 »Systematical list of the Amphipoda Hy- 



periidea». Bih. t. K. Sv. Vet. Ak. 



Handl. Bd. 11. N:o 16, p. 21. 

 1887 . »Arctic and Antarctic Hyperids». Vega- 



Exp. Vetensk. Iakttagelser. Bd. 4, 



p. 568. 



1887. »Oversigt over det vestlige Grenlands 



Fauna af malakostrake Havkrebsdyr». 

 Vidensk. Meddel. fra den Naturhist. 

 Forening i KJ0benhavn. 1887, p. 59. 



1888. »Report on the Ampbipoda». Voy. of 



H. M. S. Challenger. Zoology. Vol. 

 29, p. 1407. 



This genus, one of the oldest and best known of all the Hyperiidean genera, has 

 never been confounded with any other genus, at least with regard to its fully adult forms; 

 the young of the species belonging to this genus, on the other hand, have been described 

 as species of Hyperia. The difference between Euthemisto and Parathemisto is so small, 

 that it is somewhat doubtful, as I have said before, *) whether they really ought to be re- 

 corded as two independent genera or not. 



The first generic diagnosis, given in 1825 by F. E. Guerin-Meneville, the founder 



of the genus, was repeated in a memoir in 1828. It runs: 



»Corps oblong, compose de douze segmens; tete occupee entierement par deux yeux a 

 reseau, arrondie, non prolongee inferieurement en rostre. Quatre antennes: les superieures plus 

 courtes que la tete, courbees au bout; les inferieures beaucoup plus longues. Quatorze pieds: 

 le quatre premiers courts, diriges en avant, couches sur la bouche, et representant les deux der- 

 nieres paires de pieds-machoires des Crustaces superieurs; les quatre suivans beaucoup plus grands, 

 termines par un crochet dirige vers la queue; la cinquieme paire tres-longue dirigee vers la 

 bouche, ayant l'avant-dernier article grele, fort long, garni d'epines en dedans et termine par 

 un crochet; les quatre derniers, de moitie plus courts, diriges et conf'ormes de meme, mais sans 

 dents a l'avant-dernier article. Queue terminee par six appendices natatoires longs, aplatis, bi- 

 fides a l'extremite: trois paires des filets egalement natatoires sous les trois premiers segmens 

 de la queue.» 



Only two of the many characteristics given here by the founder of the genus have 

 generic value, namely, that respecting the elongation of the fifth pair of peraeopoda, and 

 that respecting the long uropoda. He gave also a description of the mouth-organs. 



l ) In »Arctic and Antarctic Hyperids», p. 566 and 588. 



