CARL BOVALL1US, AMPIIIPODA HYPERIIDEA. 



1840. Tyro, H. MILNE EDWARDS. Spence Bate. 1862. Catal. Amph. Crust. Brit. Museum, 



p. 308. 

 » » C. Bovallius. 1885. »Oa some forgotten genera among 



the Amphipodous Crustacean. Bin. 

 t. Sv. Vet. Akad. Handl. Bd. 10. 

 N:o 14, p. 12. 

 » » » 1887. »Arctic and Antarctic Hyperids». 



Vega-Exp. Vet. Iakttag. Bd. 4, 

 p. 551. 

 Dana. Proc. of the Amer. Acad, of 



Science and Arts. Vol. 2, p. 

 219. 

 » 1852. United States Exploring Expedition. 



Crustacea. Vol. 2, p. 834. 

 Spence Bate. 1862. L. c. p. 284. 



1850. Clydonia, DANA. 



Although the generic description given by H. Milne Edwards was a very good One, 

 Tyro has not been recognized until lately, remaining in the literature only as a name. 

 This has probably been due to the circumstance of its general habitus being too different 

 from that of most known Hyperids to allow of its being sought for within the Hyperiidean 

 tribe. It is however remarkable enough that Spence Bate could not identify it although 

 he examined closely the typical specimens of Hyperids in the collection of the »Musee du 

 Jardin des Plantes». To-day the typical specimen is lost, according to information kindly 

 given me by Professor Alphonsk Milne Edwards. Nevertheless I am fully convinced that 

 the new species described below as well as the Clydoniw of Dana and G. 0. Saks belong 

 to the old genus of H. Milne Edwards. 



A. The first pair of antennae about as long as the body. 



il 1. The third pair of uropoda without distinct outer rami 1. Tyro cornigera. 



a 2. The third pair of uropoda with distinct outer rami. 

 aa 1. The outer rami shorter than half the inner. 



aaa 1. The lateral parts of the pleonal segments excavated 2. Tyro gracilis. 



aaa 2. The lateral parts of the pleonal segments rounded. 3. Tyro Sarsi. 



aa 2. The outer rami as long as half the inner. 



aaa 3. The head not rostrate 4. Tyro atlantica. 



aaa 4. The head rostrate 5. Tyro longipes. 



B. The first pair of antennas shorter than half the body. 



b 1. The anterior margin of the femur of the fifth pair of pereiopoda serrated. 

 bb 1. The metacarpi of the first two pairs of pereiopoda not produced. 



bbb 1. The fifth pair of pereiopoda longer than the sixth 0. Tyro borealis. 



bbb 2. The fifth pair of pereiopoda shorter than the sixth 7. Tyro Clausi. 



bb 2. The metacarpi of the first two ])airs of pereiopoda produced 



anteriorly 8. Tyro marginata. 



b 2. The anterior margin of the femur of the fifth pair of pereiopoda smooth. 



bb 3. The spine-like process of the femur of the fifth pair simple .-.. 9. Tyro Tullbergi. 

 bb 4. The spine-like process of the femur of the fifth pair bifid 10. Tyro pacifica. 



