ISOPODS OF NORTH AMERICA. 



673 



Fl(i. 713.— SCYPHA- 



cklla arexicola. 

 Inner lobe of 

 first maxilla. 



( DiACiKAMMATIC. 1 



The segments of the thorax are subequal; the last two have the 

 post-lateral angles produced backward. 



All the segments of the abdomen are distinct. The first two have 

 the lateral parts covered by the seventh thoracic seg- 

 ment. The three following segments have the post- 

 lateral angles produced backward. The terminal 

 abdominal segment is narrow, produced in the middle 

 posteriorly in a long, narrow process, broadly rounded 

 at the apex. The peduncle of the uropoda extends to 

 the end of the terminal abdominal segment. The 

 branches are of nearlv equal length. 



Color of the specimens, for a long time preserved 

 in alcohol, dark l)rown, with the margins of the seg- 

 ments of a lighter brown. 



Five specimens were collected by Dr. S. D. Judd in the sand on 

 Ram Island. Woods Hole, Massachusetts, and are in the collection of 

 the U. S. National Museum. 



Family XXVIII. LIGYDID.E.« 



Body oval. Head without lateral lobes; frontal margin rounded, and 

 not distinctly defined from the epistome. First pair of antennje Avith 

 the terminal joint not furnished with sensory hairs. Second pair of 

 antenna well developed, with iiagellum multi-articulate. Buccal mass 

 prominent. Mandibles with the molar process large and broad, having 

 a finely fiuted triturating surface. Inner lobe of the first maxilUe fur- 

 nished at the tip with three plumose processes. Second maxillae also 

 furnished inside with two similar processes. Maxillipeds with the 

 palp composed of five articles; masticatory lobe truncate. 



Opercular branches of pleopods without trachete. First two pairs 

 of pleopods modified in male; inner branch terminating in a long stylet. 



ANAIA'TICAL KEY '^ TO THE GENERA OK THE FAMILY LIGYDID.K. 



a. Uropoda witli ba^al article not produced in a process at the inner distal angle; 

 branches equal in length. Last segment of abdomen large, with lateral parts 



well developed (xenus Lir/yda Rafinesque 



a^. Uropoda with basal articles i)roduc('d in a process at the inner distal angle; 

 branches nne<|u;d in Icntrth. Last segment of abdomen small, with lateral parts 

 obsolete ( Jenns Ligklnun Brandt 



128. Genus LIGYDA." Rafinesciue. 1814 



Body oval, or oblong oval; abdomen not abruptly iiarrowiM' than the 

 thorax. Terminal segment broad, with latcial parts well developed. 

 First pair of antennte with the third or terminal joint rudimentar}^, 

 nodiform. 



"See Sars for characters of family and genus. 



f> The genus Euphihi^ci a Packard is not included, as it is ])rol)ably a synonym of 

 Ligidiuiii. 



28589—05 43 



