List of Crustacea Clarlocera from Madison, Wis. 385 



ber about eight and are placed on the posterior side of the distal end of 

 the base. The flagellum is attached to the base with a distinct suture. 

 Sars calls it " distinctly articulated " in L. australis. Whether he means 

 that there is a movable joint he does not make clear. In L. occidentalis 

 there is simply a distinct suture. The flagellum is long, curved back- 

 ward, tapers to a fine point, and is fringed with long straggling sense- 

 hairs. These are far less numerous than in Latona. Most of them are 

 on the anterior side of the antennale but at the tip they are attached to 

 all sides. In this arrangement of {he hairs the structure differs from the 

 antennule of L. australis as figured by Sars. The sense-hairs are also 

 longer than he shows them and the whole antennule is about twice as 

 long, relatively, as that of L. australis. 



The antenna closely resembles that of L. australis. The basal joint is 

 exceedingly stout, so that the branches look too small for it. The dorsal 



sames is bi-, the ventral tri-articulate. The setae are -^ — M - A — 



— 1 — 4 



and the spines ^ 1 _- The basal joint bears the usual dorsal sense 



organ at the base, and at the distal end are a spine anteriorly and a 

 plumose sense-hair behind. The proximal joint of the dorsal ramus 

 bears' four well developed setae, and sometimes a fifth, proximal, seta 

 which is much smaller than the others. Its presence or absence seems 

 to depend on no law, as it is either present or absent in specimens of all 

 ages and both sexes and may be present on one side and absent on the 

 other side of the same individual. All setae are two jointed and densely 

 plumose. 



The proportionate length of individual setae differs in my specimens 

 from L. australis as figured by Sars. The terminal setae of the dorsal 

 ramus are little longer than the others in L. occidentalis. The seta of the 

 second joint of the ventral ramus is as long as the largest on the distal ' 

 joint and each is quite twice as long as any other seta on the branch. 



The post-abdomen closely resembles that of L. australis. It is short j 

 fleshy, obtusely conical, and armed with nine very small super-anal den- 

 ticles. The abdominal setae are two-jointed, plumose, each set on a 

 fleshy projection. They are a little longer than those of L. australis. 

 The terminal claws are strongly curved, and have two secondary teeth, of 

 which the distal is the longer. 



The mouth parts and legs seem to resemble closely those of the other 

 Sididce. No careful study of the legs, has, however, been made. They 

 number six pairs, as in other Sididce. 



INTERNAL ORGANS. 



In the structure of the internal organs L. occidentalis agrees closely 

 with L. australis, and I can add little to Sars' account. The general ar- 

 rangement of the organs of the head may been seen in the figures. 

 25— A. & L. 



