594 BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



ANALYTICAL KEY TO THE SPECIES OF THE GENUS ALLONISCUS. 



a. Surface of body very densely granulated. Epimera with the anterior angles ser- 

 rate Attoniscus mirabilis (Stuxberg) 



a' . Surface of body punctate. Epimera with the anterior angles not serrate. 

 6. Lateral processes of the head large, prominent. 



Attoniscus cornutus Budde-Lund 

 b'. Lateral processes of the head small, scarcely prominent. 



Alloniscus perconvexus Dana 



ALLONISCUS MIRABILIS (Stuxberg). 



Rhinoryctes mirabilis STUXBERG, Ofvers. Vet. Akad. Forhandl., 1875, No. 2, p. 51. 

 Attoniscus mirabilis BUDDE-LUND, Crust. Isop. Terrestria, 1885, p. 229. 

 Rhinoryctes mirabilis UNDERWOOD, Bull. 111. State Lab. Nat. Hist., II, 1886, p. 



363. 

 Alloniscus mirabilis RICHARDSON, Proc. U. S. Nat. Mus., XXI, 1899, p. 864; Ann. 



Mag. Nat. Hist. (7), IV, 1899, p. 332; American Naturalist, XXXIV, 1900, 



p. 305. 



Locality. California. 



Body oval, twice as long as wide, convex, very densely granulated; 

 epimera serrate on the margins. Second pair of antennae much 

 shorter than the width of the body (85:100); the fifth article of the 

 peduncle very long, not very much curved, equal in length to the 

 three articulate flagellum; the articles of the flagellum equal to each 

 other in length or the middle one sometimes smallest. 



Eyes prominent, subcircular, with numerous ocelli. 



The frontal median lobe large, produced, obtuse, extended upward, 

 equal to a fourth part of the width of the head; lateral lobes pro- 

 duced, conical, anteriorly rounded, equal to the eyes in length. 



All the segments of the thorax with the posterior margin sinuated 

 in the middle. Epimera moderately large, with the anterior angles 

 gradually more rounded posteriorly, serrate, the posterior angles 

 roundly acuminate not very much directed backward. 



Abdomen subcircular, a little wider than long, all the segments 

 equal in length, the epimera of the first and second segments vanishing, 

 those of the third, fourth, and fifth segments large, directed backward, 

 rounded on the exterior margin, serrate, almost straight on the inner 

 margin. The last segment is triangular, twice as wide as long, with 

 the posterior margins straight, roundly acuminate, rather convex 

 above and sometimes furnished with a longitudinal furrow not at all 

 deep. The uropoda have the basal article almost as wide as long, 

 depressed, with the post-lateral margin very little elevated, circularly 

 rounded, serrate, the outer branch a little flattened, subconical, with 

 the exterior margin straight, the inner margin convex, extending not 

 much beyond the inner branch in length, which extends very little 

 beyond the last segment of the abdomen. 



