42 BULLETIN 201, UNITED' STATES NATIONAL MUSEUM 



three as in Illig's figure. The eyes are somewhat differently shaped. 

 The stalk is not so long as Illig shows and the corneal portion is more 

 expanded. The flagellum of the antenna has four or five joints and 

 is apparently similar in both male and female. The telson has 12 to 

 14 spines on each lateral margin. At each corner of the slightly 

 emarginate apex are three long spines, each armed with small spinules, 

 the center spine of the three the longest. In the center of the apex is 

 a single median spine, shorter than any of those at the lateral angles. 

 Between the median spine and the lateral spines at each side are three 

 small spinules, and between the spinules are a series of eight long 

 plumose setae. In the male there is a short genital appendix on the 

 eighth thoracic limbs. The first thoracic limb has a well-developed 

 epipodite as in P. arrmger. Illig states that the endopods of the pos- 

 terior thoracic limbs have the expanded basal portion composed of 

 two joints. I am unable to detect this feature in the present specimen, 

 where the exopods have the normal single expanded basal joint from 

 which the flagellalike part takes origin. 



The pleopods in my specimens differ profoundly from those figured 

 by Illig for the female. Illig gives no description of the pleopods, 

 but from his figure of the adult female the pleopods in this sex con- 

 form to the type found in the female of P. armiger; that is, they are 

 uniramous and composed of three joints. From a consideration of 

 the pleopods of the male of P. armiger it is possible to interpret these 

 pleopods as consisting of a basal sympod and an endopod of two joints. 

 In the adult female in the National Museum collection all the pleopods 

 are biramous (fig. 5, f-j). In pleopod 1 the endopod consists of a 

 single joint and the exopod of six joints. In the remaining pleopods 

 the endopod has two joints and the exopod seven to nine joints. The 

 exopods are not flagellalike, the joints being long, slender, and cylin- 

 drical in form. The exopod in all cases is longer than the endopod. 



In the male specimen all the pleopods are again biramous and the 

 exopod is longer than the endopod (fig. 5, a-e). The sympod of all 

 the pleopods of the male is much stouter and broader than in the 

 female. In the first pleopod the endopod consists of one joint only 

 and the exopod of about 16 joints. In the remaining pleopods of the 

 male the endopod is composed of nine joints and the exopod of 16 

 joints. The exopods are flagellalike, the joints all being quite short 

 and stout with the exception of the basal joint. In the endopods the 

 two basal joints are exactly as in the female pleopods and the re- 

 maining joints form a flagellalike termination of seven joints added 

 to the normal endopod of the female. Although Illig had a male 

 specimen of his species he makes no special mention of the structure 

 of the pleopods. The structure of the pleopods is the one point which 

 makes the reference of these specimens to P. oculatus doubtful. Illig 



