78 



Bulletin Vanderbilt Marine Museum, Vol. VI 



The spine on the basis of the male fifth leg is simple, slender, 

 very acute. 



Text figure 3 — Penaeopsis macleayi (Haswell) , petasma of adult male, 

 shown from posterior side, X 6. 



The petasma is symmetrical, of the shape figured (text fig. 

 3), with the main portion consisting of a much folded membrane 

 forming a hollowed tube-like organ, the interior of which bears 

 longitudinal ridges, caused by folds of the membrane, and with a 

 median sinus on the exposed outer surface of the petasma, be- 

 tween the lateral margins of the petasma membrane ; these margins 

 become rounded distally where the main portion of the petasma 

 divides into two out-bent lateral portions, one on each side, form- 

 ing the inferior half of a short, externally bent, internally hol- 

 lowed, tubular process, with the distal aperture small ; this lower 

 half of the lower process is distinct from, but in close proximity 

 to, the upper half of the lateral process, which is externally con- 

 vex, hood-like, internally hollowed with a small, semicircular aper- 

 ture, the entire upper portion curved above, or bent over the lower 

 half of the lateral process of the petasma, the two together form- 

 ing a convex, dorsally bulbous process, with the external aperture 

 semicircular, but having just inside it a complicated convolution 

 which leads to the internal ridges and grooves of the main portion 

 of the petasma. Just above this lateral process is another process, 

 which arises from the inner lateral margin of the petasma and 

 forms a small conical process which is distinct from and curves 



