ISOPODS OF NORTH AMERICA. 



405 



six more or less broken black lines. The lines on the sides are more 

 distinct than those above. 



Head subquadrate, partially immersed in the first thoracic segment 

 and rounded on the posterior margin; sides parallel, anterior margin 



FIG. 452. CLEANTIS PLANICAUDA (AFTER MOORE), a, GENERAL FIGURE, b, FIRST ANTENNA. 

 c, SECOND ANTENNA, d, FIRST LEG. e, FOURTH LEG. /, SEVENTH LEG. 



emarginate; a deep depression or groove runs from the median notch 

 to the center of the head. The eyes are situated near the antero-lateral 

 angle; post-occipital lobe distinct; antennae with six seg- 

 ments; first very short and nearly immobile; second very 

 short and stout; the third segment is equal in length to the 

 second, but not so stout; the fourth and fifth are of equal 

 length and about one-third longer than the second and third 

 segments. The terminal segment or flagellum is lighter in 

 color, and is armed with short bristles. The 

 length of the antennae is equal to the length 

 of the head and first two thoracic segments. 

 The antennulae extend to the middle of the 

 third segment of the antennae. The first seg- 

 ment is quadrate; the second subquadrate; 

 the third is pear-shaped; the fourth segment 

 is very small. Maxillipeds with the palp 

 composed of five articles. 



The segments of the thorax are nearly 

 equal in length and breadth, the third and 

 CLEANTIS fourth being but little longer than the others. 

 PLANI- The e pi mera of the second, third, and fourth 



CATJDA. _ ' _ 



segments are very small and can not be seen 



from above. On the fifth, sixth, and seventh segments the epimera 

 are large and project well behind the margin of the segment in the 

 form of an acute angle. 



The pleon is composed of four segments; the first three are very 

 narrow; the terminal segment is elongated with subparallel sides. A 



FIG. 454. CLEANTIS 

 PLANICAUDA. 

 MAXILLIPED. 



