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Rostrum acute, narrow, 2 to 2, 5 -times as long as it is broad at base, reaching to 

 the distal third of the visible part of first antennular article and projecting straighdy forward, 

 though the extremity is a little turned downward. Rostral carina sharp, continued to just 

 behind the middle of the carapace and bearing, somewhat posterior to the orbital 

 hoods, a small, obtuse tubercle or prominence, situated nearly twice as far from the posterior 

 margin of the carapace as from the tip of the rostrum ; interorbital part of the rostral carina 

 slightly concave and concealed, in a lateral view, by the orbital hoods. Orbital region broad, 

 two-thirds the width of the carapace anteriorly ; corneae large, one and a half as long as the 

 rostrum, orbits rounded anteriorly, unarmed, anterior margin of the orbital region very slightly 

 concave. Grooves between the orbits and the rostral carina very narrow, moderately deep. 



Carapace smooth. Abdominal terga coarsely punctate, lower angle of abdominal pleura 

 subacute, especially those of the 3"^ and the 4'*^ somites. Telson narrow, twice as long as broad 

 anteriorly, whereas the distance between the posterolateral angles is little more than one-fourth 

 the length ; spinules of the upper surface inserted about twice as far from the mid-line as from 

 the lateral margins. 



Second antennular article slender, about four times as long as thick, one-third longer 

 than the visible part of the first, that is one and a half as long as the third; stylocerite reaching 

 almost to the end of first article. Basicerite with a small spine, shorter than the stylocerite. 

 Carpocerite as long as the antennular peduncle, scaphocerite in the male a little longer than 

 the antennular peduncle, but in the female as long as it, narrow, its greatest width not yet 

 one-fourth of its length. The blade, that narrows anteriorly, hardly reaches beyond the middle 

 of the terminal spine, that measures one-third of the total length of the scaphocerite ; outer 

 margin of the latter decidedly concave. In the male the blade reaches to the end of the 

 antennular peduncle, in the female it extends just beyond the end of the second article. 



Outer margin of the antepenultimate joint of the external maxillipeds unarmed, lower 

 face with a prominent undulate crest that runs from the proximal to the distal extremity ; 

 penultimate joint conical, hardly longer than thick ; terminal joint narrowing, five times as long 

 as broad at base, three times as long as the penultimate joint. 



Infero-internal margin of the ischium of the larger cheliped of the male coarsely denticulate 

 or tuberculate. Merus 3-times as long as broad, upper margin coarsely denticulate or tuberculate 

 along its whole length, unarmed at apex; infero-external margin finely denticulate, outer face 

 covered with subacute granules that are larger on the upper half, infero-internal margin armed 

 with 4 acicular spinelets and terminating in an acute tooth. Carpus armed at the infero-internal 

 angle with a sharp tooth. Chela turned outward, a little more than one and a half as long- 

 as the carapace, 3-times as long as high, compressed, about half as thick as high ; upper border 

 of the palm, which is almost 3-times as long as the fingers, rounded, without a transverse 

 groove near the articulation of the latter. 



Besides by its rostral carina, A.Sibogae is furthermore characterized by a moderately 

 deep groove on the outer face of the palm. This groove that begins near the lower end 

 of the carpus, where it is rather narrow, gradually widens until to the middle of the palm 

 and from here, slightly narrowing again, extends almost to the tip of the immobile finger; this 



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