596 BULLETIlSr 54, UNITED STATES NATIONAL MUSEUM. 



The tirst two segments of the alxlomen scarcely shorter than the 

 other seo-ments; the epimera of the third, fourth, and lifth seoments 

 strong, subtetragonal . 



The terminal abdominal segment is triangular, short, hardly twice 

 as wide as long, rather convex above. 



The basal article of the uropoda is very wide, depressed; the outer 

 branch is carinated, with the apex rounded; the inner l)ranch is inserted 

 at the inner angle of the basal article. Color gra3"ish, pale on the 

 sides. Length, 8.5 mm.; width, 5 mm,; height, 2 mm." 



ALLONISCUS PERCONVEXUS Dana. 



Alloniscui:< pcrconvexus Dana, Proc. Acad. Nat. Sci. Phila., VII, 1854, p. 176. — 

 Stimpson, Bost. Jour. Nat. Hist., VI, 1857, p. 506. — Budde-Lund, Crust. 

 Isop. Terrestria, 1885, p. 225. — Underwood, Bull. 111. State Lab. Nat. Hist., 

 II, 1886, p. 360.— 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. 



Localities. — California; Pacific Grove; Santa Bar- 

 bara; Monterey Bay; Tillamook Head, Oregon. 

 Dug at mean-tide mark from sandy shore. 



Body ovate, ver}" convex, not quite twice as long 

 as broad, mm.: 16 mm. 



Head twice as wide as long, 2 mm.: 4 nmi., with 

 the antero-lateral angles produced on either side into 

 an acute process, " horn-like," situated just in front 

 of the eye, and the front produced in the middle in 

 a large, widely rounded median lobe, extending as 

 far as the lateral process. The eyes are small, 

 oblong, composite, and situated in the antero-lateral "^ perconvexus'^^"^ 

 angles of the head close to the lateral margins. The 

 first pair of antennae are rudimentary and inconspicuous. The}^ are 

 composed of three small articles. The second pair of antennae have 



«The above description is adapted from the following one of Budde-Lund's: 



Breviter ovalis, subconvexus, obscure sed dense squamatus et punctis setigeris 

 crebratus. Antennfe exteriores corpore diniidio breviores (7:17); flagellum scapi 

 articulo quinto brevius; flagelli articulus secundus brevissimus, primus tertio sequalis. 



Processus frontales laterales majores, angustiores, prominentes, subconici; frons 

 media valde tumosa. 



Trunci annuli tres priores margine posteriore utrinque leviter sinuato; annuli 

 sequentes omnes margine posteriore medio post magis sinuato. 



Caud?e annuli duo priores ceteris annulis vix l)reviores; epimera annuli 3-4-5 

 valida, subtetragona. Annulus analis, triangulus, brevis, segre duplo latior quam 

 longior, supra convexiusculus. 



Articulus basalis pedum analium perlatus, depressus; extus carinatus, apice rotun- 

 dato; ramus interior angulo interiori articuli basalis insertus. 



Color griseus, in lateribus dilutior. 



Longitudo, 8.5 nun.; latitude, 5 mm.; altitudo. 2 mm. — Budde-Lund, Crust. Isop. 

 Terrestria, 1885, pp. 228-229. 



