4 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 122 



Name. — This ostracod is named in honor of my good friend and 

 fellow student of crayfishes and entocytherid ostracods, Miss Margaret 

 Walton. 



Dactylocy there Hart 



Dactylocythere Hart, 1962, Proc. Acad. Nat. Sci. Pliiladelphia, vol. 114, no. 3, p. 129. 



With the description of the 2 new species included here, 18 species 

 have been referred to this genus, which ranges from Kentucky and 

 West Virginia to Alabama and from New Jersey to South Carolina. 

 The following key will assist in the recognition of these ostracods. 



Key to Species of Dactylocythere 



1 Ventral portion of peniferum with two or more small acute projections; 



finger guard very slender and tridentate; clasping apparatus almost 

 U-shaped with subterminal flare; accessory groove reduced or obsolete. 



leptophylax (Crawford, 1961, p. 238) 



1' Ventral portion of peniferum without projections; finger guard seldom 



slender, if tridentate, comparatively stocky; clasping apparatus 



variable but never with subterminal flare; accessory groove well 



developed 2 



2(1') Apex of clasping apparatus without denticles 3 



Apex of clasping apparatus with two or more denticles 4 



3(2) Clasping apparatus scythelike, sometimes with a single tooth on internal 



border of horizontal ramus, otherwise unadorned. 



falcata (Hobbs and Walton, 1961, p. 379) 

 3' Clasping apparatus without teeth but with two or three grooves appear- 



ing to encircle distal portion of horizontal ramus. 



striophylax (Crawford, 1959, p. 157) 



4(2') Shell with posteroventral projection 18 



4' Shell without posteroventral projection 5 



5(4') Accessory groove extending dorsally much beyond level of dorsal 



extremity of spermatic loop 6 



5' Accessory groove never extending dorsally more than slightly beyond 



level or dorsal extremity of spermatic loop, sometimes not reaching 



loop 8 



6(5) Vertical ramus of clasping apparatus distinctly arched 7 



6' Vertical ramus of clasping apparatus almost straight. 



mecoscapha (Hobbs and Walton, 1960, p. 19) 

 7(6) Proximal and distal ends of clasping apparatus subparallel. 



prionata (Hart and Hobbs, 1961, p. 178) 

 7' Proximal and distal ends of clasping apparatus at angle of 50° to 70° 



to each other 19 



8(5') Dorsal margin of accessory groove not reaching spermatic loop . . 20 

 8' Dorsal margin of accessory groove reaching spermatic loop, almost to or 



slightly beyond dorsal extremity 9 



9(8') Width of clasping apparatus at major bend more than 1.5 times least 



width (excluding proximal articulation) of vertical ramus .... 10 



9' Width of clasping apparatus at major bend less than 1.5 times least 



width (excluding proximal articulation) of vertical ramus .... 13 



10(9) Horizontal ramus of clasping apparatus with one tooth on internal 



border chalaza (Hobbs and Walton, 1962, p. 45) 



