A REVIEW OF THE MYSIDACEA 



95 



Male pleopods very distinctive, especially those of the second and 

 third pairs ; the endopod of all the pleopods of the male is composed 

 of a single short joint; the exopod of the first pair (fig. 27, a) is much 

 longer than the endopod and is composed of four joints ; in the second 

 pair (fig. 27, b) the sympod is very long and stout, iy 2 times as long 

 as the exopod, the endopod is single jointed and furnished with 8 

 or 9 delicate plumose setae, the exopod is 7- jointed, the terminal 

 joint furnished with 2 long plumose setae; in the third pair (fig. 

 27, c) the sympod is about 2y 2 times as long as broad, shorter and not 

 so stout as the sympod of the second pair and shorter than its own 

 exopod, endopod single jointed and furnished with 2 short curved 

 spines at the apex, the exopod is long and modified in the most extra- 

 ordinary way into a very complicated copulatory organ (fig. 27, c) ; 



Figure 27. — Gastrosaccus johnsoni Tattersall: a, First pleopod of male, X 33%; b, second 

 pleopod of male, X 33 %; c, third pleopod of male, X 25; d, fourth pleopod of male, X 

 33%; e, fifth pleopod of male, X 33%; /, carpopropodus of endopod of one of posterior 

 thoracic limbs, X 33%; g, one of setae of carpopropodus of one of posterior thoracic 

 limbs, enlarged. 



fourth and fifth pleopods of the male (figs. 27, d-e) very similar to 

 one another, with a short rectangular sympod, a single- jointed endopod 

 and a 2- jointed exopod, all furnished with the usual long plumose 

 setae. 



Length of adults of both sexes, 10 mm. 



Occurrence. — East coast of the United States: Albatross station 

 2272, 2 adult females, 1 adult male. West Indies: The Johnson- 

 Smithsonian Expedition collected two lots of material from Luispena 



