AN UNDIVIDED WKIST 239 



carinatus of S. I. Smith, who says that the basal joint of 

 the first antennaa is ' furnished externally with a large 

 lamellar process terminating anteriorly in an acute angle 

 in front of the eye,' a description ill-suited to the epithet 

 rudimentary. 



Legion 3. Monocarpinea. 



The wrist, or fifth joint of the second pair of trunk-legs, 

 is not subdivided, and generally the chelge of this pair are 

 larger than those of the first. 



Spence Bate arranges in this group eleven families 

 the Thalassocaridaa, Atyidaa, Pontoniidaa, Caricyphida3, 

 AcanthephyridcB, Palaamonidaa, Nematocarcinidse, Tropio- 

 caridaa, Stylodactylidas, Pasiphaeidaa, Oodeopidee, among 

 which the first differs from all the rest by having the first 

 pair of trunk-legs simple, and the last differs from all the 

 rest by having the second pair simple. The Tropiocaridae 

 do not seem to deserve a separate existence, without 

 further consideration. 



Family 1 . Thalassocaridce. 



The first trunk-legs are simple, the second chelate. 

 Three genera are assigned to the family, one of them, 

 Diapliorupus, Spence Bate, 1888, founded on what ' is 

 evidently the immature condition of some undetermined 

 form.' 



Thalassocclris, Stimpson, 1860, takes the place of 

 Regulus, Dana, 1852, the latter name being pre-occupied. 

 The species as yet known belong to the Pacific, and are 

 regarded as a link connecting the Pandalidse with the 

 Palasmonidas. 



Family 2. Aiyidce. 



The carapace is dorsally smooth, with flattened ros- 

 trum ; the scale of the second antennae short. The man- 

 dibles have a molar process and cutting edge, but no ' palp.' 

 The third maxillipeds are four-jointed and pediform. The 

 first and second trunk-legs are chelate, with spoon-shaped 

 fingers. The telson is flattened, truncate. 



