6 7 



The rostrum of the male from Stat. 2io a , which has the same size as the preceding, 

 is just as long as the antennular peduncle, ^-dentate and extends horizontally forward : it fully 

 resembles the quoted figure in the "Illustrations", but a line uniting the apices of the 5 proximal 

 teeth ascends very slightly upward, of the 4 following it descends slightly downward. Fifth 

 abdominal somite 7,5 mm. long, 6 th 10,5 mm., telson 15 mm., the telson like in the male 

 from Stat. 185. 



The ova-bearing female from Stat. 217 is about 86 mm. long, from tip of rostrum to 

 end of telson. The rostrum is a little longer than the antennular peduncle, reaching to the 

 middle of the antennal scales ; the upper border, which is straight and armed with 10 teeth, 

 rises somewhat, obliquely, upward, though the apex runs again horizontally forward; the unarmed 

 distal extremity measures al most one-third the length of the toothed part of the upper border. 

 The lower margin runs like a S, appearing concave above the single tooth, which is directed 

 horizontally forward. Fifth abdominal somite 7,75 mm. long, 6 th 11,75 mm., telson 15,5 mm.; 

 the latter like in the two preceding specimens. Ova very numerous, small, 0,7 — 0,8 mm. long. 

 The young specimen from Stat. 48 is 36,5 mm. long, the carapace, rostrum included, measuring 

 8,5 mm. The rostrum, f-dentate, reaches to just beyond i st antennular article ; a line uniting 

 the apices of the 3 first teeth, ascends slightly upward, but from here the lower margin descends 

 slightly downward, while the unarmed tip runs horizontally forward. The tooth on the lower 

 margin, that reaches almost as far as the foremost tooth of the upper, extends horizontally forward. 

 Fifth abdominal somite 2,75 mm. long, 6 th 5,5 mm., so that the latter appears in this young 

 specimen just twice as long as the 5 th , while in adult specimens it is only about half again 

 as long; the telson, 6,25 mm. long, though longer than the endopodite of the uropods, is 

 slightly shorter than the exopodite. 



In Acanth. curtirostris the brown coloured cornea appears, when looked at from above, 

 a little less broad than the eyestalk and there is no ocellus; the apex of the ocular papilla 

 or spine at the inner border of the eyestalk appears in the egg-bearing female subacute, in the 

 other specimens rather blunt;.in the adult specimens the inner margin of the papilla forms a 

 straight line with that of the eyestalk, the papilla being contiguous to the cornea or embracing 

 it, but in the young individual from Stat. 48 the obtuse papilla is turned obliquely inward, so 

 that its inner margin makes an angle with that of the peduncle; this is also the case in the 

 young specimen from Stat. 141, long 25 or 26 mm., but in the two young specimens from 

 Stat. 185 the papilla runs nearly as in the adult. 



Like in other species of this genus the keel of the 4 th tergum bears a fine notch, which 

 in this species is situated in its posterior fifth. According to Alcock (1. c. 1901) the legs of the 

 3 rd pair should be not longer than the 4* and 5* pairs; in all our specimens, however, the 

 3 rd pair are the longest of all, while those of the 4 th and 5 th successively decrease in length. 

 In the adult egg-bearing female the legs of the 3 ld pair extend to the apex of the antennal 

 scales, those of the 5 lh only to the middle of these appendages; in the male specimens the 

 three posterior legs are a little shorter. 



General distribution: Arabian Sea (Alcock); Bay of Bengal (Alcock); Andaman 

 Sea (Alcock); from off San Diego, California, to the Gulf of Panama (Faxon, Rathbun). 



