. Bulletin - United States National Museum. Science. THE SESSILE BARNACLES. 313 spur, wliich is wholly united with the basiscutal angle. The carinnl lobe is narrow, situated high, and shows a feAv short crests for the depressor muscle. The labrum has a broad, nearly straight edge, the middle fourth having a series of 18 strong teeth (fig. did). The mandible has three large teeth and a pectinated lower point having eight slender teeth (fig. 91a). The maxilla has a pair of large upper spines followed by two smaller spines above the small notch. The median part bears a group of about 8 rather lar
. Bulletin - United States National Museum. Science. THE SESSILE BARNACLES. 313 spur, wliich is wholly united with the basiscutal angle. The carinnl lobe is narrow, situated high, and shows a feAv short crests for the depressor muscle. The labrum has a broad, nearly straight edge, the middle fourth having a series of 18 strong teeth (fig. did). The mandible has three large teeth and a pectinated lower point having eight slender teeth (fig. 91a). The maxilla has a pair of large upper spines followed by two smaller spines above the small notch. The median part bears a group of about 8 rather large spines. The lower third protrudes, and bears about 10 large and small spines. There is a group of short spines on the lower edge. The prominence of the lower part is a chief feature (fig. Olr).. •rtMAAMAAWWWi,^,,.^ Fig. 91.— withehsi. a, mandible, b, eleventh segment op cirrcs vi. Cj maxilla. (1, DPPEK MAIKilN OF THE The first cirrus has rami of 9 and 5 segments, the posterior branch two-thirds as long as the anterior. Cirrus ii has 9 and 8 segments, the rami proportioned as in cirrus i. Xone of the spines in the distal segments are pectinated or plumose. Cirrus iii has rami of 19 segments, bearing three pairs of spines. Cirrus vi has rami of 23 segments, also with three pairs of spines (fig. 915). The chief characteristic of this species is the weak articulation of the scutum and tergum; the articular ridge of the scutum is short and extremely weak, and the articular furrow is shallow. The shape of the tergum is peculiar. These features will at once separate C withersi from the smooth, unworn forms of C. stellatus. The ab- sence of pits for the adductor and depressor muscles is also notable. In the mouth-parts, the labrum and mandible diil'er widely from. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly res
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