392 



BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



Body ovate, two and two-thirds times longer than broad, 6 mm. : 

 16 mm. Length of abdomen three-eighths the length of entire body, 

 6 mm. : 16 mm. 



Head with deep median excavation or notch in front. In the median 



Fin. 435.— Synidotea PicTA (After Benedict), x 3. a, Typical form. ?;, Variety. 



line, just below the frontal notch is a large and prominent tiil^ercle, 

 narrow and elongate. On either side in line with this tubercle is a 

 small rounded tubercle. These three tubercles are placed in a trans- 

 verse line between the eyes. A little in front of these tubercles, and 

 halfway between the median notch and the lateral 

 margins are two tubercles, one on either side in front 

 of the eye. Back of the three tu])ercles in tranverse 

 series are two rugosities, one on either side of the 

 median line, and posterior to these is a low ridge pro- 

 duced in a median tu])ercle. The eyes are large and 

 round, compound in structure, placed about the mid- 

 dle of the head and a short distance from the lateral 

 margin. The first antenna^ have the basal article short 

 and not expanded; the second and third articles are 

 about equal in length; the fourth is a little longer than 

 the third. The first antenna^ extend to the end of the 

 third peduncular article of the second pair of antenme. 

 The basal article of the second antennae is inconspicu- 

 ous from a dorsal view; the second, third, fourth, and fifth are each 

 successively a little longer than the preceding article. The flagellum 

 consists of ten articles. When retracted the second antennae extend 

 to the middle of the third thoracic segment. The maxillipeds have 

 a palp of three articles. 



The first four segments of the thorax arc^ longer than the last three. 

 In all the epimera are firmly united with the scgnuMits. Along the 



Fig. 436.— Synido 

 tea picta. Max 

 illiped. x 27^ 



