Boone, Crustacea, Cruises of "Eagle" and "Ara," 1921-28 53 



Family: LEUCOSIIDAE. 



Subfamily : Leucosiinae. 



Genus: persephona Leach. 



Persephona edwardsii Bell. 



Plate 10, fig. A. 



Name: This species was named in honor of the distinguished 

 French scientist, Prof. Henry Milne Edwards, of the Paris Museum. 



Diagnostic characters: This species is undoubtedly closely affili- 

 ated with Persephona orhicularis Bell, from which it is distinguished 

 by the different coloration, being uniformly pale buff ; by the fact that 

 this species is uniformly slenderer and has the frontal part of the cara- 

 pace narrowed anteriorly and somewhat produced, and the pterygos- 

 tomian angle and tooth of orhicularis is obsolete in edwardsii. The 

 three posterior spines in edwardsii are similarly placed, except that the 

 median spine is only half as high above the submedian spines as in 

 orhicularis. The male abdominal belt has the first, second and third 

 segments narrow, hinge-like, the third segment is closely fused with 

 the succeeding segment but has a weak divisional line; the fourth, 

 fifth and six segments are completely anchylosed ; the seventh segment 

 is small, subtriangulate, with the lateral margins convergent, the tip 

 evenly rounded. 



Type: Founded on two specimens collected in the Galapagos 

 Islands, depth 6 fms., and believed to be no longer extant. 



Distribution : Galapagos Islands, Panama, and Perlas Islands, Bay 

 of Panama. 



Material examined : Two males, taken at Saboga, Anchorage, Per- 

 las Islands, February 19, 1928, establish the first record of the species 

 from Perlas Islands. 



Technical description : Carapace moderately globose, slightly 

 longer than wide, 22 mm. long to base of posterior spine, 20 mm. maxi- 

 mum width, convex, with the frontal part narrowed anteriorly and 

 somewhat produced, the pterygostomian angle obsolete, no tooth. The 

 frontal region is narrow, depressed medially but not produced to a 

 point, the frontal line heavy, wavy; the preorbital angle blunt, 

 rounded ; the postorbital angle rounded, a trifle more prominent than 

 the preorbital angle ; the upper ocular border with three closed sinuses. 



