ISOPODS OF NORTH AMERICA. 



691 



a narrow dark colored, dentate cutting edge, but no palp. First max- 

 illae with the inner plate short and furnished with three short ciliated 

 setae, the upper one much shorter than the lower two, which are of 

 subequal length ; outer plate narrow and armed with live curved teeth. 

 Second maxillae narrow, with two very small ciliated plates on the 

 inner margin near the rounded tip. Inner plate of the maxillipeds 

 with several short, densely ciliated processes on the transverse distal 

 margin and a large ciliated seta on the inner side; palp five-jointed, 

 the terminal joint minute. 



" Legs very spiny below; dactyls short, furnished with several setse 

 and one or two spines below, near the tip. Uropods slender, fully 



FIG. 732. LlGIDIUM GRACILIS (AFTER HOLMES), a, MAXILLIPED. 6, GENERAL FIGURE. C, FIRST LEG. 



one-half the length of the abdomen; peduncle oblong, flattened, the 

 inner angle strongly produced backward; rami slender, microscop- 

 ically scabrous but devoid of spines; inner ranius exceeding the outer 

 in length, but slightly more slender, the tip furnished with setae. 



"The body is furnished with scattered fine short hairs, which are 

 more conspicuous on the posterior margins of the segments. 



''Length ?\ inch." HOLMES. a 



The above description is quoted from Proc. Cal. Acad. Sci., (3), III, 1904, p. 318, 

 and is made originally from the three type specimens of Allonwcus maculosus Harford, 

 which Mr. Holmes identifies with Styloniscus gracilis Dana, the description of which 

 follows: 



Corpus gracile. Abdomen paulo oblongum, subovatum, thorace postico subito 

 paululo angustius, segmentis 3 tio, 4 to, 5 toque lunatis. Styli caudalis basis brevis, 

 vix duplo longior quam latus, extus ad medium subito angustior. Antennae externse 

 fere nudae, flagello ferme 14 articulato, nudo, articulos basis duos precedentes longi- 

 tudine fere aequante. Long. 5 mm. 



As in other species of this genus, the outer antennae have not the double genicu- 

 lation characterizing the Oniscidae. The surface of the body is smooth; yet there 

 are a few exceedingly minute hairs, especially along the posterior margin of the seg- 

 ments of the abdomen. The branches of the caudal stylets in the specimen are 

 mutilated. DANA, Proc. Acad. Nat. Sci. Phila., VII, 1854-55, p. 176. 



