M Y S I D E A. 



The absence of a palpus from the mandible appears to show that 

 the species cannot be young of any of the Palaemonidae, as for example, 

 the genera Alpheus or Cryphiops. The caudal segment has the same 

 general form as in the Furciliae, and is without the moveable setae, 

 which give a barb-like character to this segment in the Euphausias. 



CALYPTOPIS INTEGRIFRONS. 



Carapax anticd integer, transversus, oculos omnino tegens, posticd dorso 

 productus et acntus. Antennae internee biftdce, processu articuli primi 

 duplo longiore quam arliculus proximus. Segmentum abdaminis pos- 

 tremum truncatum, angulis obtitsis, extremitate spinulis pectinato, spi- 

 nulis tribus angulorum posticorum lonyioribus, latere ad medium spi- 

 nulam gerente. 



Carapax in front entire, transverse, wholly covering the eyes, behind 

 dorsally much prolonged and acute. Inner antennae bifid, process 

 of first joint twice longer than next joint. Last abdominal segment 

 truncate, angles obtuse, extremity pectinate with spinules, three 

 on the angles longer, lateral margin at middle bearing a spinule. 



Plate 45, fig. 9 a, animal, enlarged ; b, upper view, showing eyes 

 beneath carapax ; c, caudal extremity ; d, inner antennae ; e, outer 

 antennas; /, mandible; g, first pair of legs, h, second pair; i, third 

 pair. 



Pacific, north of island of TJpolu, six miles from the coral reef. Col- 

 lected, February 24, 1841. 



Length, two lines. Colourless. The spiniform process of the first 

 joint of the inner antennae extends to apex of base. The two branches 

 are one-jointed, and are much shorter than preceding joint. The outer 

 antennae have a one-jointed base, and two one-jointed branches; the 

 branches are more than half the length of the preceding portion and 

 terminate in a few long hairs or setae. Only three pairs of legs were 

 much developed, the others being rudimentary. Abdominal legs not at 

 all developed. Mandible has a denticulate apex and a spiniform process 



171 



