138 Proceedings of the Biological Society of Washington. 



record certain data not included in the earlier literature where 

 this species was several times confused with other species, and 

 with the hope that other workers may become interested in the 

 species and further the knowledge of its North American distri- 

 bution. 



Panulirus laevicauda Latreille. 



Carapace about as long as the abdominal segments including the anterior 

 third of the caudal fan; covered with stout spines, the more prominent of 

 which are arranged in ten more or less regular longitudinal rows; spaces 

 between the major spines are almost completely covered with lesser spines 

 which are broader basally, sharp-tipped and ringed with a circle of close-set 

 plumose setae; all the spines are directed upward and forward. The side 

 plates of the carapace are more freely articulate than in P. argus or P. 

 guttatus. 



Orbital spines compressed laterally, but less so than those of Panulirus 

 argus or P. guttatus, deeper dorso-ventrally, and slightly more elevated 

 than in argus or guttatus. Eyes prominent, shining black. Anterior to 

 the frontal horns there are four long equal and equally spaced green spines, 

 between the latter near the base of the second pair are several weak spines 

 clothed with setae. There is a convex ridge extending from the base of the 

 orbital spines to the extreme frontal margin, this is much more prominent 

 than in argus or guttatus. 



The antennae have the basal article short on the outer dorsal surface, 

 produced and tapering to an acute point on the inner dorsal surface, also 

 on the inner ventral surface ; there is a very strong spine on the inner dorsal 

 angle of this joint, another about half as strong on the outer dorsal angle, 

 below the latter are two very minute spines. The inner posterior dorsal 

 part of the basal joint is produced into a convex-concave triarticulate 

 scale, that slides over forming the animal's sound-producing organ. The 

 second joint of the antennae is about one and one half times as long as the 

 first and less oblique distally, but with a strong spine on the inner distal 

 margin preceded by two less strong; there is another strong spine in the 

 median dorsal area of the margin with two lesser spines just preceding it, 

 and another weaker spine on the outer lateral margin; there are several 

 small spines on the outer lateral and ventral surfaces; the third article is 

 almost as long as the second, almost evenly produced distally, with a series 

 of three strong subequal spines on the inner lateroventral margin, another 

 strong spine on the median dorsal area of the margin, another similar spine 

 on the outer lateral margin, there are seven or eight lesser spines scattered 

 over the surface of third article; the flagellum is about twice as long as the 

 body and consists of slender uniformly tapering rings; the flagellum is set 

 with somewhat regularly placed rings of small spines at intervals and 

 fringed along the proximal part on the inner ventral margin with fine close- 

 set setae. 



The antennules have the basal joint extending a trifle beyond the tip of 

 the second peduncular joint of the antennae, the second article is two-thirds 



