. Bulletin - United States National Museum. Science. 186 BULLETIN 75, UNITED STATES NATIONAL MUSEUM. curved, deeply sunken below the disk scales, widely separated throughout. Upper arm plates wider than loh^^, with a convex or straight distal margin and a strongly convex, often angular, proximal margin; thus somewhat broadly pentagonal with only the two distal, lateral angles marked; they are much swollen and widely separated. Interbrachial spaces below rather broad, somewhat heart-shaped, cov- ered by irregular plates wliich are large at the margin but become very small near the oral shield.
. Bulletin - United States National Museum. Science. 186 BULLETIN 75, UNITED STATES NATIONAL MUSEUM. curved, deeply sunken below the disk scales, widely separated throughout. Upper arm plates wider than loh^^, with a convex or straight distal margin and a strongly convex, often angular, proximal margin; thus somewhat broadly pentagonal with only the two distal, lateral angles marked; they are much swollen and widely separated. Interbrachial spaces below rather broad, somewhat heart-shaped, cov- ered by irregular plates wliich are large at the margin but become very small near the oral shield. Genital slits short but rather con- spicuous. Oral shields rhombic or pentagonal, about as wide as long. Adoral plates long and narrow, about as wide without as within, where they meet; oral plates very small. Oral papillae about five on a side and one at apex of jaw, the outer ones are truncate, but the inner are more or less sharply pointed; be- tween the penulti- mate and antepenulti- mate papilla? are sev- eral small granules, which apparently serve as tentacle scales to the oral tentacle pore. First under arm plate pentagonal, about as wide as long; _, secontl plate nearly -v.^^-^^ ^ triangular, but trun- FiG. 85.—ophiomitra bythiaspis. X 5. a, from above; b, from catcd at the angles, below; c, side view of two arm joints near disk. wider than lono"" Suc- ceeding plates nearly tetragonal, much wider than long, widely sep- arated from each other. Side arm plates very large, meeting both above and below; each plate carries, on rather a conspicuous vertical ridge, six or five long slender arm spines, of which the uppermost, which may equal two joints, is the longest (sometimes the second is the longest), smoothest, and sharpest, while some of the lower, shorter spines are quite rough near the tip. Tentacle scale single; those on the basal pores are very large and broadly oval and are often accompanied by a second, smaller scale; bej^ond the third pair of pores the
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Keywords: ., bookauthorun, bookcentury1800, bookdecade1870, booksubjectscience
