(574 CRUSTACEA. 



pair, which are nearly equal. The second joint of the last pair is 

 much shorter than the thoracic segment. The basal scale of the ex- 

 terior antennae is longer than the eyes, and of the same length as the 

 first joint of base of the first antennae. The second joint of the base 

 of these antennae is quite short, not one-fourth the preceding. 



The organs of the mouth observed were the same in number as 

 already stated. None of the legs were furnished with palpi, or even 

 rudiments of them, as far as observed; but the first or second pair had 

 a fouette, which was extended back under the carapax, and was kept 

 in constant motion. 



Thompson's figure of his species (PL 7, fig. 2, Zool. Res.) represents 

 a female, judging from the abdominal appendages ; and yet the sixth 

 abdominal segment has two prominent teeth below. In this respect 

 it differs from the species here described. 



LUCIFER ACICULAEIS. 



Segmentum antennale carapace brevius, acut& rostratum et utrinque 

 acutum. Oculi clavati, segmento antennali paululo breviores. Seg- 

 mentum abdaminis sextum valde elongatum lamellis caudalibus valde 

 longius, feminse infra integrum, segmentum caudate lamellcegue totce 

 longitudine vere cequoe. 



Antennary segment shorter than carapax, acutely beaked and acute on 

 either side. Eyes clavate, a little shorter than cephalic segment. 

 Sixth abdominal segment much elongate, considerably longer than 

 caudal lamellas, entire below in female ; caudal segment and lamellae 

 of nearly equal length. 



Plate 45, fig. 3 a, animal, enlarged ; b, side view of extremity of 

 abdomen ; c, dorsal view ; d, base of posterior legs, with rudiment of 

 a palpus. 



Harbour of Rio Janeiro. Collected one specimen, December 25, 

 1838. 



Length one-eighth of an inch. Colourless or whitish. Thoracic 

 segment, in dorsal view, three times as wide anteriorly as antennary 



