196 CAIIL BOVALLIUS, AMPHIPODA HYPERIIDEA. I 2. HYPEKIID^. 



Hyperia agilis. 



Syn. 1853. Uyperia ajilis, i. D. DANA. — United States Exploriug Expedition. Crusta- 



cea. Vol. 2, p. 986, pl. 67, tig. Ila— lid- 

 » )) » Spence Bate. 1862. Catal. Amph. Cnist. Brit. Museum, p. 296, 



pl. 49, tig. 3. 

 M » n C. BovalJjIus. 1887. »Systematioal list of tho Anipliipoda liy- 



periidea.i) Bih. t. K. Sv. Vet. Ak. Handl. 



Bd. 11. N:o 16, p. 17. 



I have not met with any specimen of this species in the collections which I have 

 examined hitherto, but judging from the description and the drawings given by Dana I 

 believe that it raay be a good species. Spence Bate says in 1862 that the description of 

 Dana «so closely resembles that of Lestrigonus Gaudicliaudii, that 1 should have united 

 them, had not Dana described the tlagella of this species as being uniarticulate». 



For that reason I for niy part should not hesitate to unite theni if the other charac- 

 teristics agreed, the less so because Dana in his diagnosis expressly says ^mrticulo ultimo 



interdum obsolete articulato^i. But, as uiay be seen from the above diagnosis, there 



are other distinctions between the two species as for instancc, the narrow femur of the 

 tirst two pairs of pera^opoda, the relation between the length of the two first pairs and 

 the third and fourth pairs, and between the length of these last and the hfth, sixth, and 

 seventh pairs, etc. 



The Latin diagnosis of Dana runs: 



»Caput mediocre, pigmentis oculorum angustis. Thorax longus, epimeris totis brevibus, 

 truncatis. Antennfe longiusculffi, dimidii thoracis longitudine subfequfe; 2da3 parce longiores, 3- 

 articulata?, non teretes, articulo ultimo longo et remote pubescente, interdum obsolete articulato; 

 Ima; 5-articuläta?, articulo 4to crasso longoque et infra ciliato, ultimo minuto. Pedes 4 antici 

 subaequi, coxis angustis; 6 postici mediocres; setis brevibus et paucis.» 



From the short description of Dana I give the following details: 



In front view of tlie head, the antennary area is large, nearly square, and the pigment 

 occupies nearly all the space on the side of it. 



»Pigment of eyes much smaller than usual, black. 



Aiitennai rather long (half as long as thorax), subequal; superior five-jointed, fourth joint 

 stout, long, ciliate below, the last minutc; inferior slightly the longest, three-jointed, not terete, 

 last joint long, and remotely hairy. — — 



The inferior antennaj have two short basal joints, and then a long, compressed, subulate 

 joint, which is a little hairy. 



Thorax long, all the epimerals short, truncate. The seven tlioracic segments about equal. 



The four anterior legs have the last three joints, or the terminal portion straight, and 

 apparently admitting of upward flexion alone; they terminate in a nearly straight spine. Four 

 anterior feet subequal, coxfe narrow. Six posterior of moderate length, sette short and few. 



First three abdominal segments with the posterior angle on either side of each, prominent 

 and acute. 



While swimming, the legs are generally folded up across the venter; it swims by means 

 of the abdominal legs, and the extremity of the abdomen.» 



