KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 21. N:() 5. 5 



Sea, c. borealis; by exaniiiiing thc mouth-orgaris ho rccognizcd thc relationship of 

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

 px'esent treatise tried to prove the identity of Tyro and Clydonia, and in 1887 lic proposed 

 the family-name Tyronidce for these aiiiiuals. 



The fauiily Tyronidaj is less closely allied with the other Hyperids than any of the 

 other families, and in the general habitus of the aninials shows a certain resemblanee to 

 some of the Gaiuraarids; still they are true Hyperids. From this reason Tyronida; are 

 placed as the fii"st family next to the Gauiioarids. 



In the form of the head and the eyes the Tyronidaj show the elosest relation to 

 Laticeolidce and Vihilidce, the first pair of antennaj somewhat resemble those of Minwnectidce 

 and Thauuiatopsidce ; the form of thc second pair points towards TryphienidLV and the 

 following families. The mouth-organs tlu'oiigh the form of thc mandibles remind onc of 

 the families Paraphroniniidce and Phronimidce. 



The sexual dimorpliismus seeras to be restrieted to the prcscnce (o^) or rudimentary 

 state (?) of the seeond pair of antcinui'. 



As to the anatomical peculiarities I refer to the seeond \)u\-i of this treatise, only 

 calling attention to the very imperfect de\clopmcnt of tlie eyes, (jiutc coiitrary to thc statc 

 of these organs in most of the other families. 



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

 mentions that his speeimens werc taken at the surface (jf thc open sea. Saks has taken 

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

 sitical. I myself captured many speeimens in the Caribbean Sea during the ex[)cdition 

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

 free on the surface of the sea. I eould ucver lind any case of parasitismus. 



Hitherto only onc genus is known. 



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



Diagn. Capnl brevius quam altiiis. Ante.niiw priuii paris pediinculo urasso, articulis tribiis in iinum 

 coalitis fonuato. I'edes pereii primi et sccundi pariuiu siiupliccs, nou chclati, pedes quinti 

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

 elongati, ramis internis cuni pedunculis coalitis. 



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

 thc three coalesced joints. The first and second pairs oi' pereiojjoda are simple, not chelate. 

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

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

 coalesced with the peduncles. 



Syn. 1840. Tyro, H. MILNE EDWARDS. — — Histoire Naturelie des Crustacés. 



Tom .3™% p. 80. 

 » » Dana. 1Sö2. United States Exploring Expedition. 



Crustacea. Vol. 2, p. 980. 



