116 MR. T. SCOTT ON ENTOMOSTRACA 



Genus Onc^a, Philippi. 



Onceea, Philippi, Wiegmana's Arcliiv, 1843. 

 Antaria, Dana, Proc. Amer. Acad. Sci. 1849. 



Onc^a obtusa (Dana). 



1843. Onceea venustat, Philippi, Wiegmanu's Archiv, pi. 111. fig. 3. 



1852. Antaria obtusa, Dana, Crust. U.S. Expl. Exped. p. 1230, pi. Ixxxvi. figs. 13 a-c. 



1883. Onceea obtusa, Brady, Report Chall. Copep. p. 120, pi. li. figs. 1-11. 



Habitat. Station 2, surface, 5, 25, and 50 fathoms, January 1st (night collections). 

 Station 9, surface, 25 and 50 fathoms, January 10th (day collections). Lat. 1° 55' 5" N., 

 long. 5° 55' 5" E., 10, 20, 30, 260, 360, and 460 fathoms, January 22nd (day collections). 

 Bananah Creek, Congo River, surface, February 7th (day collection). Loanda Harbour, 

 surface, Pebruary 13th (day collection). 



Onccea obtusa was observed in 119 tow-nettings, 60 of wdiich were surface and 59 

 under-surface gatherings. The under-surface tow-nettings ranged in depth from 2 to 

 460 fathoms. 20 of the surface and 41 of the under-surface gatherings were day col- 

 lections ; 34 of the surface and 18 of the under-surface gatherings were night collections, 

 as shown by the formula : — 



26 day collections. 



r lb clay collect! 

 60 surface \ 3^ ^^„^^ ^j^to 



Tow-nettings 119 , .-, n tm; 



(.59 under-surface P^^^'^y^^^^*^- 

 (. 18 night ditto. 



This was one of the most common and most generally distributed species in the 

 ' Buccaneer ' collection ; many of the specimens carried ovisacs, and though the collection 

 had been for several years in spirit a considerable proportion of the OnccBce retained 

 much of the vivid coloration so characteristic of the species. 



ONcasA GRACILIS (Dana). (PI. XIII. figs. 4-12.) 



1853. Antaria gracilis, Dana, Crust. U.S. Expl. Exped. p. 1229, pi. Ixxxvi. fig. 11 a. 



Length I'l mm. Cephalothoras narrow, ovate. Abdomen elongate, slender ; the 

 breadth of the first abdominal segment is somewhat less than two-thirds its length, and 

 one-third the length of the abdomen, exclusive of the stylets ; the second segment is 

 scarcely half the length of the first, and equal to the combined length of the next two ; 

 the third segment is nearly twice the length of the last, while the caudal stylets are 

 somewhat longer than the last abdominal segment (fig. 12). The anterior antenna? are 

 similar to those of OnccBa obtusa, but are more slender ; the relative lengths of the joints 



are nearly as in the formula : — 



4 . 4 . 13 . 2 . 1 . 3 



r~2 3 4 5 6' 



The last joint of the posterior antennte about as long as the preceding one, but more 

 slender and furnished with four long, stout, ajjical setae, and another seta near the base. 

 Mouth-appendages nearly as in Onceea obtusa, except that the last joint of the posterior 

 foot-jaw is elongate and armed with a long, powerful, nearly straight terminal claw. 



