10 CARL BOVALLIUS, AMPHIPODA IIYPERIIDEA. 



Pedes septimi paris tertiam partem longitudinis pedum quinti paris superantes. Segmenta 

 uri duo ultima coalita. Pedes uri lati, minute serrati; rami externi primi et secundi parium 

 minutissimi, rami externi tertii paris distincti, tertiam partem longitudinis pedunculi fere 

 superantes; rami interni trium parium pedunculis paullo breviores. Telson anguste lingula- 

 tum, ramo externo tertii paris paullo brevius. 



The body is keeled dorsally. The head is a third deeper than long, provided on the upper 

 side with two divergent keels. The first pair of antenna' are a little shorter than the 

 body. The first, pair of pereiopoda with elongated carpi and dactyli. The fifth pair are 

 much longer than the sixth; the femur has the anterior margin feebly serrated, the 

 posterior distinctly serrated; it is much shorter than the three following joints together; 

 the apical spine-like process is twice longer than the genu, straight; the tibia is much 

 shorter than the carpus; the carpus is almost three times longer than the metacarpus. 

 The seventh pair are longer than a third of the fifth pair. The last two ural segments 

 are coalesced. The uropoda are broad, minutely serrated; the exterior rami of the first 

 and second pairs are very minute, those of the third pair are well developed, a little 

 longer than a third of the peduncle; the interior rami of all the three pairs are almost 

 as long as the peduncles. The telson is tongue-shaped, narrow, only a little shorter than 

 the exterior ramus of the last pair of uropoda. 



Colour. White to yellowish. 



Length. 15—30 mm. 



Hal). The north, tropical and south Atlantic. (D.M. S.M. U.M.) 



Syn. 1885. Tyro Sarsi, 0. BOVALLIUS. »On some forgotten genera among the Amphipodous Crustaeea». 



Bib. t. K. Sv. Vet. Ak. Handl. Bd. 10. N:o 14, p. 15, 

 fig. 3. 



Tyro Sarsi is the largest of all known Tyronida? and seems to be the most common 

 species. It is closely allied to Tyro atlantiea but distinguished from it by many characteris- 

 tics, as will be seen below. 



The body is somewhat depressed or rather meagre, the dorsal keel is broad and 

 runs from the point where the divergent occipital crests meet to the urus. The integument 

 is very hard, and rather rough. The line indicating the articulation of the epimerals con- 

 tinues along the lower parts of the sides of the pleonal segments, forming a low keel. 



The head is concaved on the upper side between the two divergent crests, which 

 run from the highest point of the head down to the bases of the first pair of antennse. 

 The head is a little shorter in the male than in the female; the anterior side is truncated 

 and a little concavated. 



The eyes (PI. I, fig. 3) consist of 15 ocelli, a large one in the centre and seven close 

 round it, the other seven being ranged in an outer circle, so that the whole forms a some- 

 what elevated bulb, without distinct facets. 



The first pair of antenna* (Pi. I, fig. 4 and 5) are a little longer in the female 

 than in the male. The peduncle is very thick, the three original joints are coalesced into 

 one. In very young specimens the peduncle is three-jointed, the basal joint much the 

 largest. The peduncles occupy nearly the whole surface of the anterior side of the head. 



