OPHIURANS OF THE PHILIPPINE AND ADJACENT WATERS. 113 



are directed obliquely outward, and then suddenly form a very 

 obtuse angle and continue outward perpendicularly to the median 

 interradial line; after a certain distance they reunite, each passing 

 over a very acute angle, with the two distal sides which together 

 form an obtuse and very rounded angle. The adoral plates are 

 situated on either side of the mouth shields, and are not in contact in 

 the median interradial line ; they are broadened outwardly and taper 

 gradually as far as their proximal end, which is pointed and which 

 lies at the same level as the proximal angle of the mouth shield. The 

 oral plates are triangular, short, and low. The mouth papillae are 

 four in number on each side; their form is rather irregular, espe- 

 cially that of the two proximal papillae, which are flattened with the 

 free border irregularly jagged or lobed; the two distal papillae have 

 the base much broadened and they taper rather abruptly beyond the 

 middle. The unpaired terminal papilla is broadened and flattened, 

 broader than those preceding, and its free border shows three or 

 four small, irregular, and unequal lobes. In the second specimen 

 from station 5629 (pi. 27, fig. 5) the form of the mouth papillae is 

 very much more regular, and it is the same in the two other speci- 

 mens. In that from station 5623 (fig. 9) the mouth shields have not 

 quite the same- outlines as in the others, and the lance-head shape is 

 less marked. This is especially because the proximal angle and the 

 two lateral angles are more or less rounded, and the sides are some- 

 what incurved. 



The upper arm plates are rather large, triangular, broader than 

 long, with a rather acute proximal angle and an almost straight dis- 

 tal border. They are separated from the base of the arm outward 

 by an interval at first very short but gradually elongating. At some 

 distance from the base of the arms these plates become a little longer 

 than broad and slightly bell-shaped. 



The first under arm plate is quadrangular or trapezoidal with the 

 distal border a little shorter than the proximal border. The two or 

 three following plates are quadrangular, with a rather narrow proxi- 

 mal border, and an extremely broad and convex distal border passing 

 over sharp angles into the sides which are very divergent and strongly 

 excavated by the tentacle scale; these plates are very much broader 

 than long. Beyond the disk the plates become pentagonal with an 

 obtuse proximal angle, and they soon become a little longer than 

 broad, at the same time becoming separated by a very narrow 

 interval. 



The rather strongly projecting side arm plates bear eight or nine 

 large, thick, strong cylindrical spines, with the tips blunted, at least 

 in those which are found on the ventral side; the dorsal spines are 

 more slender and pointed. These latter, on the first segments, come 



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