20 G. O. SAES. PRELIMINÅBY NOTICES ON THE SCHIZOPODA. 



but with the main stem quite obsolete. Three posterior pairs of 

 branchiæ very complex. 



Remarks. Of this genus, the first which has been established 

 in the family Euphausiidæ, only the typical form described by 

 M. Edwards has hitherto been known. All the other forms which 

 have been referred by subsequent authors to this genus, belong in 

 my opinion to different genera. In the restriction wherein the 

 genus is tåken here, it comprises, beside the typical form, also S 

 new species from the 'Challenger' Expedition, two of which how- 

 ever only are represented by solitary specimens, of which it has 

 not been possible to make a closer anatomical investigation. The 

 genus is chiefly characterised by the structure of the 7th pair of 

 legs, which is of the very same form as the preceeding, so that 

 only the last pair remains rudimentary. 



24. Thysanopoda tricuspidata Edw. 



Thysanopoda tricuspidata, Milne Edwards, Histoire naturelle des Crustacés, 

 Tome II, pg. 463, pl. XXVI, fig. 1-6. 



Form of body not much elongated and rather compressed. 

 Carapax armed with two strong lateral denticles at the inferior 

 margin above the bases of the Ist and 7th pair of legs; rostrum 

 rather produced. straight and sharply pointed; an anteriorly directed 

 somewhat flattened spine above at some distance behind the rostrum. 

 Third postabdominal segment armed with a strong dorsal spine in 

 the middle of the posterior margin; 4th and 5th segment with 

 similar, but much smaller dorsal spines. Two anterior pairs of 

 epimera curved anteriorly, the first rather large and complex, 

 divided in two acuminate lobes, the foremost partly covered by the 

 carapax. Last segment elougated, somewhat produced at the end 

 above; præaual spine ungviform, with a small denticle at the 

 posterior margin. Eyes rather large, pyriform. Antennular peduncle 

 of moderate size, subcylindric, with a small lanceolate lappet above 

 at the end of the Ist and 2nd joints. Antennal scale slightly sur- 

 passing the 2nd joint of the antennular peduncle, oblong, apex 



