Boone, Crustacea, Cruises of "Eagle" and "Ara," 1921-28 33 



spine; the epimeral angle is also an acute tooth directed down and 

 posteriorly. The remaining thoracic segments resemble those of alba 

 and so do the abdominal segments, the only differences being that the 

 tooth at the postlateral angle of each segment of mantis is longer 

 and sharper than are those of alba, and that all the carinae of the 

 fifth segment of mantis each terminate in a small spine, as do also 

 those of the sixth segment. There is a median longitudinal carina 

 extending from the third thoracic segment to the posterior margin of 

 the abdominal segment. The telson has the same general shape and 

 proportions as that of alba, but the marginal dentition differs, mantis 

 having the median ridge terminating posteriorly in a spine beneath 

 which there is a nodular granule at the base of the slit-like median 

 incision, on either side of which there are four small, rounded teeth, 

 those from the center being the largest and adjacent to a sharp, 

 longer, pointed tooth, which is followed on the outerside by five acute, 

 triangulate teeth, beyond which there is one long, acuminate tooth 

 with a median keel extending back a short distance on the telson, and 

 which is separated on the outside by a short, triangulate tooth from 

 a long acuminate tooth with a median keel running back onto the tel- 

 son; about opposite the proximal termination of this keel there is on 

 the lateral margin a blunt tooth, which is continuous with the lateral 

 carina of the telson. 



The peduncle of the uropod is similar to that of alba and has a spine 

 at its rostral margin; the proximal half of the outer blade differs in 

 having seven acute movable spines, successively increasing in length 

 from the proximal to the distal, along the distal half of its outer 

 margin; the distal half of the outer blade is oval, eiliate; the inner 

 blade is small, elongate, with a rounded apex. The produced inner 

 angle of the peduncle has the same general shape as that of alba, with 

 the inner lateral margin carinate and the inner distal angle produced 

 into a curved, elongate, acuminate tooth whose apex is in line with 

 that of the innermost long spine of the telson ; the rounded node lying 

 between this spine and the one forming the outer distal angle is de- 

 cidedly smaller than that of alba; the outer distal angle of mantis is 

 a long, acuminate tooth. 



The eyestalk is very short, stocky ; the cornea is very large, renif orm, 

 set obliquely upon the stalk, the long diameter of the cornea twice its 

 own short diameter, and about twice the length of the stalk. 



The inner antennae are similar to those of alba. 



The external antennae differs from alba in the shape of the proximal 



