594 BiTLLirriN rA, united states national museum. 



ANALYTICAL KEY TO THE SPECIES OF THE GENUS ALLONISCUS. 



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

 rate AUoniscns mirabilis (Stuxberg) 



«/. Surface of body punctate. Epimera with the anterior angles not serrate. 

 b. Lateral processes of the head large, proroinent. 



AUoniscus cornutus Budde-Lund 

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



AUunisciis perconrexus Dana 



ALLONISCUS MIRABILIS (Stuxberg). 



RkmoryclcsmlvahUk Stuxberc;, Of vers. Vet. Akad. Forhaudl., 1875, No. 2, p. 51. 

 AUoniscus mirabilis Budde-Lund, Crust. Isop. Terrestria, 1885, p. 229. 

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



363. 

 AUoniscus 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 a,s long as wide, convex, very densely granulated; 

 epimera serrate on the margins. Second pair of antenniv much 

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

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

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

 other in length or the niiddle one sometimes smallest. 



Eyes prominent, subcircular, with numerous ocelli. 



The frontal median lol)e 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 e3'es in length. 



All the segments of the thorax with the posterior margin sinuated 

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

 graduall}' more rounded posteriorly, serrate, the posterior angles 

 roundly acuminate not very much directed backward. 



Abdomen sul)circular, a little wider than long, all the segments 

 equal in length, the epimera of thelirstand 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 sti'aight, 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. 



