50 



DISCOVERY REPORTS 



Mastigopus ca. 5 mm. More than five times length of body. The kink in hfe is so 

 situated that the flagellum is first directed backwards and then bent sharply at an acute 

 angle. It can, however, be straightened out and held at angles to the body so that the 

 kink hardly shows. 



Mastigopus ca. 6 mm. (Fig. 41). Flagellum about six times as long as body. In the 

 figure the kink is not visible. 



Fig. 41. S. pcctiiiatus. a, Mastigopus, 6 mm. ; b, setae on flagellum. 



Sergestes sargassi Ortm. Hansen 



Hansen, 1922, p. 154, Mastigopus. 

 Illig, 1927, p. 330, S. nudus, Mastigopus (?), fig. 103. 

 Cecchini, 1928Z), p. 38, Mastigopus (?). 



Ortmann (1893, p. 69) mentions an Acanthosoma which he thought was that of S. sargassi, but 

 without figure or adequate description. 



Material. We have no larvae which can with certainty be referred to this species, 

 and the Mastigopus is rare at Bermuda. The Acanthosoma described below, of which 

 one specimen was taken in 1935 and one in 1938 at Bermuda, cannot be proved to belong 

 to S. sargassi, but there is no other species to which it can be attached. Its colour and 

 general resemblance to S. pectinatiis support the identification. 



Description. Acanthosoma 2 (Figs. 42, 43). Length 3-0 mm. Rostrum 0-96 mm. 



Rostrum denticulate, longer than antennule, with long basal spine. Carapace as wide 

 as long. Supraorbital spines denticulate, longer than eye; anterior lateral spines long 

 and stout, with several long basal spinules; posterior lateral spines with long basal 

 spinules. Hepatic spines long, slender, denticulate. Posterior dorsal spine very long, 

 with spinules. Dorsal organ large. 



