1S8 ^r. Anton Stuxberg on new 



would belong at one time of its life to the one and at another 

 time to the other. 



EXPLANATION OF PLATE XV. A. 



Fit/. I. Dexamine autantica. 1 «. First <rnathopod. \h. Second gnatlio- 

 pod. 1 c. Third pereiopod. 1 d. Hand and linger of third 

 perciopod, more highly magiiitied. 



Fig. 2. Seba ISitundersii. 2 a. f^'irst gnathopod. 2 b. Second gnathopod. 

 2 c. Fifth pereiopod. 



Fit/. 3. Sphtvroina ahjoense. 3 a. Underside of tail-piece. 



XXIV. — Desa'ijjtions of some new North-Attierican 

 Lithobioidae. By Anton Stuxberg. 



1. Ltthohius monticoluy n. sp. 



Lamina cephalica subcircularis, eadem fere latitudine ac lon- 

 gitudine, margine postico snbrecto, setis punctisque im- 

 pressis sparse praidita. Antennce mediocres, articulis 20 

 maximam partem cylindi'aceis, setis rigidis vcstitis compo- 

 sitce. Oculi longitiidine triplo majore qiiarn altitudine, 

 ocellis 7-9 in 2 series longitudinales digestis. Coxcc pedum 

 maxillarium secundi paris dentibus 6 + 6 conicis, acutiuscn- 

 lis, nigerrimis armatfe. Scuta dorsualia rugulosa, sparsis- 

 sime pilosa, 2°, 4°, 6°, 7°, 9°, 11°, 13° margine postico recto, 

 angulis posticis rectis vel rotundate rectangulis, 1°, 3°, 5°, 

 8°, 10°, 12°, 14° margine postico elevato sinuato, angulis 

 panim productis, rotundate acuminatis. Scutum ventrale 

 ^gum fovea longitudinali profmidiore, cetera omnia plana. 

 P(yri coxales numerosi, rotundi, in 3^ series irregulares 

 dispositi. Pedes primi paris calcaribus 2, 3, 2. Pedum 

 analium articulus primus calcaribus binis, altero majore in- 

 feriore, altero minore laterali armatus. Pedes anales ungue 

 singulo, calcaribus 1,4,3,1 — 1,4, 3, 2 armati. Color non 

 manifestus. 



Longitudo coi-poris 18 millim. 



Hob. in SieiTa Nevada ( G. Eisen) . 



2. Ltthohius pusio, n. sp. 



Lamina cephalica subcircularis, eadem fere latitudine ac lon- 

 gitudine, setis minimis sparsissimis. Antennce breviores, 

 articulis 20 plerumque brevibus, crassis compositae, ex 

 quibus ultimus longissimus, longitudine quatuor praece- 

 dentes junctos aequans. Oculi ocellis 6 magnis in 2 series 



