332 CAUL BOVALL1US, AMFHIPODA I1YPERIIDEA. I. 2. FHRONIMID^E. 



Genus 1. DAIRELLA, C. BOVALL1US, 1887. 



Diagll. Caput magnum, plus minusve globosum. Perceon latum, post nou angustatum. Pedes pertei 

 primi et secundi parium simplices, nun subcheliformes, sequentibus simillimi ac paullulo 

 solum breviores. Pedunculus pedum uri ultimi paris valde dilatatus. 



The head is large, and more or less globular. The perceon is broad, not narrowed behind. 

 The first and second pairs of perceopoda are simple, not subcheliform, very similar to the 

 following, and only a little shorter. The peduncle of the last pair of uropoda is much 

 dilated. 



Sj'll. 1887. Dairella, C. BOVALLIUS. "Systematical list of the Amphipoda Hyperii- 



dea». Bib. t. K. Sv. Vet. Ak. Haiidl. 

 Bd. 11. N:o 16, p. 24. 

 » » Th. Stebbing. 1888. "Report on the Amphipoda». Voy. ofH.M. S. 



Challenger. Zoology. Vol. 29, p. 1342. 



The genus Dairella is one of the most remarkable among the Hyperiidean genera 

 beeause it is »isopodous», i. e., all the pairs of pera:opoda are subsimilar in shape, none 

 of them forming a prehensile organ of any kind. 



The type for the genus was Paraphronima calif ornica, proposed by me in 1885; 1 ) 

 at the same time as the new genus Dairella was instituted I gave a short description 

 of a new species from the Atlantic, Dairella latissima. 



Stubbing in 1888 proposed the new specific name Dairella Bovallii for a species 

 which however is no doubt identical with D. latissima. He says that D. Bovallii 

 is distinguished from D. latissima »by the wrist of the first gnathopods not being twice 

 as long as the hand, and by having the peduncles of the first pair of uropods much longer, 

 instead of shorter, than those of the second pair». The first difference is due to a mis- 

 understanding of the wording in my diagnosis, caused by the omission of two commas; 

 the passage runs, »Carpus of first pair of pereiopoda twice broader and longer than 

 metacarpus", instead of »Carpus of first pair of pereiopoda twice broader, and longer, 

 than metacarpus". The other difference exists but is only sexual, so that in the male 

 specimens the peduncle of the first pair of uropoda reaches fully to the apex of the ped- 

 uncle of the second pair, but in the females it does not reach as far down. At the time 

 when I wrote the original diagnosis I did not know any male specimens. 



The characteristics used for the specific distinction are: 



1. The size of the head. 



2. The length of the fifth pair of perseopoda. 



3. The relation between the length of the femur and of the carpus in the fifth pair. 



4. The breadth of the femur in the last three pairs of perseopoda. 



5. The form of the rami in the last pair of uropoda. 



x ) C. Bovallius. »On some forgotten genera among the Amphipodous Crustacea». Bih. t. K. Sv. Vet. 

 Ak. Handl. Bd. 10. N:o 14, p. 11. 



