NO. 2253. DESCRIPTIONS OF TEN NEW ISOPODS— BOONE. 601 



Superior antennae about 1.5 mm. long, basal joint short, stout; sec- 

 ond and third article slightly longer, very slender; flagellum short, 

 four-ringed, bearing olfactory filaments. Inferior antennae very 

 slender, as long as the body, (6.1 mm.), basal joint short, anterior 

 margin produced into serrations Avhich encup the base of the second 

 article; second article slenderer posteriorly, slightly swollen an- 

 teriorly, twice the length of the first; third and fourth articles of 

 equal length, one-third longer than the second; fifth and sixth ex- 

 tremely short, subequal, flagellum less than last peduncular segment. 

 The maxilliped has a palp of five articles. 



Thorax : First, second, and third segments of equal length but of 

 gradually increasing width ; lateral parts of first segment expanded, 

 surrounding the posterior part of head, anterolateral angles extend- 

 ing to the eyes; epimera of the second and third segments distinct, 

 lateral margin broadly expanded, lobate; fourth 2.5 mm. long, de- 

 cidedly wider anteriorly than the preceding segments, thence nar- 

 rowing posteriorly (greatest width 2.2 mm., least width 0.9 mm.), a 

 prominent median dorsal tubercle summits the greatest width and 

 a similar less prominent one the least width of this segment; the 

 boarder epimera occupy the anterolateral angles; posterior margin 

 deeply excavate; fifth segment 0.3 mm. long, the sixth less, the sev- 

 enth equals the sixth ; epimera on last three segments small, angular, 

 occupying the anterolateral angles. 



Abdomen: This consists of two segments, the first of which is 

 short and evenly vaulted above, while the terminal segment is long, 

 narrow, and produced on the sides near the base into an acute process 

 or expansion of the lateral margin, and a second similar but less 

 prominent process two-thirds of the length of the last near the pos- 

 terior end ; the extreme termination being blunt and triangular. 



First four pairs of legs slender, forward-directed, densely hir- 

 sute, each successive pair longer than the preceding; the last three 

 pairs ambulatory, gradually decreasing in length. 



The holotype (Cat. No. 50401, U.S.N.M.), an adult female, was 

 collected by the Venice Marine Biological Station, on seaweed, at 

 Venice, California. 



This species is at oncie distinguished from previously described 

 Astacillas by its greater size and the unique pyramidlike shape of the 

 fourth thoracic segment. 



Suborder ONISCOIDEA. 

 Family ONISCIDAE. 



PHILOSCIA MINUTISSIMA, new species. 



Plate 92, fig. 2. 



Body elongate-ovate, about two and a half times as long as wide, 

 4 mm., 1.6 mm. Head about twice as wide as long, with the frontal 



