ISOPODS OF NORTH AMERICA. 



291 



EXOSPH/EROMA YUCATANUM (Richardson). 



Sphseroma yucalanum RICHARDSON, Proc. U. S. Nat. Mus., XXIII, 1901, p. 534. 

 Locality. Cape Catoche, Yucatan. 

 Depth. 24 fathoms. 



Head transverse; eyes situated at the extreme post-lateral angles. 

 First pair of antennae short, reaching the posterior 

 margin of the head; flagellum six -jointed. Second 

 pair of antennae, with a flagellum composed of ten 

 joints, extend to the posterior margin of the second 

 thoracic segment. 



First thoracic segment longer than any of the 

 following segments, its post-lateral angles produced. 

 The remaining segments of equal length; epimera 

 produced laterally into acute processes. 



First abdominal segment with suture lines. Last segment termi- 

 nating posteriorly in an obtuse point, on either side of which is a small 

 tooth. The base of the segment bears three low tubercles, one in the 

 inediau line and one on either side. The uropoda are short, not reach- 



FIG. 305. EXOSPH.E- 

 ROMA YUCATANUM. 

 ABDOMEN. 



FIG. 306. EXOSPH.EKOMA YUCATAM'M. (t, MAXILLIPED. X ~7\. b, FRONTAL LAMINA AND CLYPEUS. 



(DIAGRAMMATIC.) 



ing the post-lateral teeth. Both branches are equal in length and 

 width, the outer branch pointed, the inner branch truncate. 



Surface of body smooth; color bluish. 



One specimen was taken at Cape Catoche, Yucatan. 



Type.C&t. No. 23905, U.S.N.M. 



