1978] 
Moore & Orth — Bryothinusa 
187 
wide; second segment somewhat narrower and almost as long as 
first; third segment narrower and longer than second, tapered to 
bluntly pointed apex. Mandible (Fig. 3) curved, pointed, with a 
large internal apical tooth followed by four blunt denticles in the 
apical half. Ligula (Fig. 4) rounded at apex, about as long as wide, 
about as long as first segment of labial palpus. Labial palpus (Fig. 4) 
two-segmented, segments longer than wide, second segment a little 
narrower than first, tapered to bluntly pointed apex. Gular sutures 
most approximate in the middle, widely divergent ahead and 
behind. 
Thorax . — Pronotum almost twice as wide as long, apical margin 
straight, sides gently arcuate, base straight, angles narrowly rounded, 
with a few scattered setae. Mesonotum and metanotum very similar 
to pronotum. 
Abdomen with the first six segments nearly parallel sided, seventh 
segment narrower than sixth, eighth segment narrower than seventh. 
First six segments with two discal setae, a row of about eight setae 
along the basal margin and scattered setae at the sides. Eighth 
segment with distinct raised opercula for an osineteriuin, the area 
Figure 9. Low tide at White Point City Park, Los Angeles County, California, 
habitat of Brythinusa catalinae Casey. 
