Boone, Crustacea, Cruises of ''Eagle" and "Ara," 1921-28 49 



the pair of submedian, acuminate, triangulate teeth whieli are sepa- 

 rated from the median tooth by a concave margin and which form the 

 outer angles of the median lobe. There is a smaller lobe on either side 

 of the median lobe and separated from it and also from the outer lat- 

 eral lobe by a deep sinus on each side. This intermediate lobe is two- 

 fifths as wide basally as the median lobe, tapering forward, forming 

 a rather broad, triangular tooth which has the outer lateral margin 

 more accentuated than the inner, the tip decidedly acuminate, and 

 extending as far forward as the apex of the external lobe. The ex- 

 ternal lobe is a trifle wider than the intermediate lobe and has its inner 

 angle forming a short, bluntish tooth whose apex forms the outer 

 angle defining the sinus which separates the two lobes. The external 

 angle of the outer lobe forms a slender, triangulate, spine-like tooth 

 which, as stated previously, extends as far forward as the apex of the 

 intermediate lobe ; the margin of the external lobe between the inner 

 and outer angle is concave. The sinus between the median and inter- 

 mediate lobes extends backwards as an open channel for a distance 

 equal to four-fifths of the length of the rostrum ; from the base of the 

 open channel a decided concave groove and the open channel are con- 

 tiguous and are set with long, spinose setae which project obliquely 

 above and across the opening, making it difficult to distinguish where 

 the sinus ends and the groove begins, which difficulty is increased by 

 the abundance of setae on the adjacent frontal region. The sinus 

 between the intermediate and external lobe is as deep as the one be- 

 tween the median and intermediate lobe and has a similar concave 

 groove behind it. Behind the postorbital tooth and separated from its 

 base by a distance equal to almost one-third of the width of the cara- 

 pace at this point, the lateral margin is produced into a prominent, 

 sharp, triangulate tooth which is directed obliquely outward and for- 

 ward. This spine is very prominent, being wider basally, longer and 

 more acuminate than the external orbital spine. The lateral margins 

 of the carapace are carinated and finely crenulate or bluntly serrate ; 

 they are also fringed with close, fine, plumose setae which arise from 

 the lower face of the carapace and are especially abundant on the 

 pterygostomian region. 



The abdomen of the female narrows posteriorly and is vaulted and 

 bent under, the first segment being 4.5 mm. wide and 2 mm. long, 

 with the lateral margins relatively straight and the posterior margin 

 arcuate ; the second segment is slightly wider and shorter than the first 

 and has its lateral margins slightly convex; the third segment is a 



