DOBOPYGUS. 135 



extended investigation tlian I have had the oppor- 

 tunity of bestowing upon them. I believe, however, 

 that the representations given in these plates, though 

 unavoidably incomplete, will be found to be correct as 

 far as they go. 



2. Doropygus atjkitus, Thorell. PI. XXIX, figs. 1 — 11; 



Doropygus auritus, Thorell. Om Krustaceer i Ascidier, &c.,p. 50, 

 tabs, vii and viii, fig. 10 (1859). 



Adult female. — Thoracic segments separated at 

 their junctions by deep sulci, and produced into 

 gibbous prominences ; head as seen from the side 

 sub triangular ; caudal segments (fig. 11) stout and 

 slightly curved, and armed at the apices with four or 

 five curved hook-like spines. Anterior antennas 

 (PL XXIX, fig 2) having the first two joints 

 greatly dilated, and bearing several stout setge, but 

 no spines, 8-jointed. The swimming feet do not 

 differ materially from those of D. pulex, except 

 that the inner branch of the first pair (fig. 8) 

 is only 2- jointed, and the setae of all are distinctly 

 plumose. The second joint of all — more especially of 

 the outer — branches is much shorter than the first 

 and third. Fifth pair of feet (fig 10) small, oblong- 

 ovate, bearing a few irregularly placed, minute, 

 marginal cilia, the basal portion having also a small 

 setiferous tubercle or rudimentary external branch. 



