154 U.S. NATIONAL MUSEUM BULLETIN 23 6 



the color pattern of the spechnens, a characteristic which is next to 

 worthless in alcohol-preserved specimens. Several specimens are 

 known only in one sex or at an immatm-e stage ; descriptions by other 

 authors arouse the suspicion that their material consisted of several 

 species (e.g., E. australis Nicholls). I refrain therefore from giving a 

 key — almost an impossibility for the males, for which the structure of 

 leg 2 is of fundamental value — but the synonymy (as far as it can be 

 unraveled) of all species is given. Eudactylopus anomala Sewell is 

 excluded (see above). 



Eudactylopus andrewi andrewi Sewell, 1940 



Figures 56-59 



Dactylophusia latipes Thompson and A. Scott, 1903, pp. 238, 268. 

 Eudactylopus latipes A. Scott, 1909, p. 219, pi. 63 (figs. 8-14). 

 Eudactylopus latipes. — Lang, 1948, p. 561, fig. 227 (no. 2) (in part). 

 Eudactylopus latipes f. andrewi Sewell, 1940, p. 201, figs. 31-33. 



I have pointed out above that it is necessary to substitute a new 

 name for Dactylopus latipes T. Scott, 1894. The name available for 

 this species is Eudactylopus latipes f. andrewi Sewell, 1940; the name 

 andrewi for Sewell's form must be raised to specific level. Sewell 

 (loc. cit.), in his discussion of E. latipes, has divided this species into 

 two forms, f. typica and f. andrewi, of which typica conforms to T. 

 Scott's original description and is characterized by 9-segmented 

 antennules; f. andrewi has 7-segmented antennules. As an explana- 

 tion of the difference in antennular structure between the Atlantic 

 (f. typica) and Indo-Pacific (f . andrewi) representatives of this species, 

 Sewell suggests a different mode of development, with the result that 

 "in the form that occurs in the Indo-Pacific region the attainment of 

 sexual maturity in both sexes is accompanied by retention of certain 

 immature characters." The only point in favor of this suggestion 

 which I can take from Sewell's account is the fact that in the Vth 

 copepodite stage the antennule is 7-segmented. A more reasonable 

 explanation, at least for the time being, seems to me that both forms 

 are subspecifically or probably even specifically different and I have 

 expressed this supposition in their names. The Indo-Pacific form, 

 which now should become the nominate subspecies, should be referred 

 to as Eudactylopus andrewi andrewi Sewell, 1940; the Atlantic form, 

 as Eudactylopus andrewi atlanticus, new subspecies. The Indo- 

 Pacific form, material of which occurs in the Ifaluk collection, will 

 be described below; no material of the Atlantic form is available at 

 present. 



Material. — Loc. 431, 1 ad. 9, 1.05 mm.; 1 ad. d', 0.83 mm. 



Description. — The following is based on the above-mentioned 

 specimens; both have been dissected and the appendages mounted. 



