KONGL. SV. VET. AKADKM1ENS HANDLINGAR. BAND. 21. N:0 5. 5 



Sea, C. borealis; by examining the mouth-organs he recognized the relationship of 

 Clydonia with the Hyperids and ranged it with this tribe. In 1885 the author of the 

 present treatise tried to prove the identity of Tyro and Clydonia, and in 1887 he proposed 

 the family-name Tyronidce for these animals. 



The family Tyronida; is less closely allied with the other Hyperids than any of the 

 other families, and in the general habitus of the animals shows a certain resemblance to 

 some of the Gammarids; still they are true Hyperids. From this reason Tyronidaa are 

 placed as the first family next to the Gammarids. 



In the form of the head and the eyes the Tyronida? show the closest relation to 

 Lanceolidw and Vibilidce, the first pair of antenna? somewhat resemble those of Mimoneetidce 

 and ThaumatopsidoB ; the form of the second pair points towards Tryphcenidce and the 

 following families. The mouth-organs through the form of the mandibles remind one of 

 the families Paraphronimidce and Phronimidce. 



The sexual dimorphismus seems to be restricted to the presence (o 71 ) or rudimentary 

 state (?) of ihe second pair of antenna?. 



As to the anatomical peculiarities I refer to the second part of this treatise, only 

 calling attention to the very imperfect development of the eyes, quite contrary to the state 

 of these organs in most of the other families. 



The biological notices concerning these animals are very scarce indeed. Dana 

 mentions that his specimens were taken at the surface of the open sea. Sars has taken 

 Tyro borealis from a depth of 200 to 300 fathoms; he supposes that it may be para- 

 sitical. I myself captured many specimens in the Caribbean Sea during the expedition 

 of H. Swed. Majesty's Corvette Balder 1881 — 82, and later in the Pacific, all swimming 

 free on the surface of the sea. I could never find any case of parasitismus. 



Hitherto only one genus is known. 



Genus 1. TYRO, H. MILNE EDWARDS, 1840. 



Diagll. Caput brevius quam altius. Anteruice priori paris pedunculo crasso, articulis tribus in ununi 

 coalitis formato. Pedes pereii priori et secundi pariura simplices, non chelati, pedes qninti 

 paris saltatorii. Epimera distincta. Pedes plei robusti, pedunculis permagnis. Pedes uri 

 elongati, ranris interois cum pedunculis coalitis. 



The head is shorter than deep. The first pair of anteniice with thick peduncles, formed of 

 the three coalesced joints. The first and second pairs of pereiopoda are simple, not chelate. 

 The fifth pair are transformed into jumping legs. The epimerals are distinct. The pleopoda 

 are well developed, with very large peduncles. The uropoda are elongated, the inner rami 

 coalesced with the peduncles. 



Syil. 1840. Tyro, H. MILNE EDWARDS. Histoire Natiuelle des Crustaces. 



Tom 3 mc , p. 80. 

 » » Dana, 1852. United States Exploring Expedition. 



Crustacea. Vol. 2, p. 980. 



