DOROPYGUS. 135 



extended investigation than 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 AURITUS, Thorell. PI. XXIX, figs. 1 11; 



Doropygus aurilus, 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 antennae 

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

 greatly dilated, and bearing several stout setae, 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. 



