CAKL BOVALLIU.S, AM 1'11I1'()]JA II Vl-KUlI DKA. 



1810. Tyvo, II. JMlJjiNJi KDVVAIUJS. SriiNcn J5atjc. lHti2. Catal. Amph. Crust. Brit. Museum, 



p. 308. 

 » » C. ISovALLius. IHHi). »Oa some forf^ottftii genera among 



the Ainphipodou.s Crustacoa». Bih. 

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

 N:o 14, p. 12. 

 » » » 1881. »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. CbjdoHia, DANA. 



AlthoLigli the gencric descriptioii given by H. Milne EuwAiiDs was a vury good one, 

 Tyro has not becn recognized uiitil lately, reuiaining in the literature only as a name. 

 This has prol)ably been due to the circuiustance of its general habitus being too dififerent 

 from that of niost known Hyperids to allow of its being sought for within the Hypcriidean 

 tribe. It is however remarkable enoiigh that SrENCE Bate could not identify it although 

 he exarained closelj' the typical specimens of Hyperids in the collection of the »Musée du 

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

 given me by Professor Alphonse Milne Euwakds. Nevertheless I am fully convinced that 

 the new' species described below as well as the Clydonue of Dana and G. O. Saks belong 

 to the old genus of H. Milne Edwards. 



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



a 1. The third pair of uropoda without distinct outer rami _. I. Tyro cornigeia. 



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

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



aaa 1. The lateral parts of the pleonal segments cxcavated .... 3. Tyro gracilis. 



aaa 2. The hiteral 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 antenna; shorter than half the bod}'. 



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

 bl) 1. The metacarj)! of the first two pairs of pereiopoda not produced. 



bbh 1. The fifth pair of pereiopoda longer than the sixth 6. Tyro borealis. 



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



bb 2. The metacarpi of the first two pairs of pereiopoda produced 



anteriorly 8. Tyro niarginata. 



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 Tiillbergi. 

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



