PACiiARD.] PHYLLOPODS OF NORTH AMERICA. 303 



Subfamily ESTHERIAN^ Packard. 



Carapace or shell obloug, more or less flattened or oval, sometimes 

 subglobose, with distinct lines of growth. From 18 to 27 or 28 pairs of 

 feet; in the males the two anterior pairs of feet with hands; the end of 

 the abdomen with dorsal spines and two pairs of very long, large, curved, 

 terminal spines. 



Synopsis of the genera. 



Shell oval, more or less globose, with 18-22 lines of growth, 

 amber-colored; flagella of 2d antennse 11-17 jointed; 

 24 to 27 or 28 pairs of feet UstJieria. 



Shell large, broad oval, much flattened, subtriangular, with 

 about 18 lines of growth, a haft-organ present. Flagella 

 of 2d antennae 12-13 jointed; 18-22 i)airs of feet Limnadia. 



Shell narrow-ovate, rather prominent behind the umbones, 

 with 4-5 lines of growth. A haft-organ present. Fla- 

 gella of 2d autennse 9-10 jointed; 18 pairs of feet EuUmnadia. 



Genus ESTHERIA Eiippell. 

 Plates III, IV, V, XXIV, XXV, XXVI, figs. 1, 2, XXVII. 



Eslheria Riippell, Museum Senckenbergiannm. Bd. II, Heft. 2. Ueber Estheria dalia- 



lacensis Ruppell, von H. Strauss-Durckbemi. 1657. 

 Cijsicus Audouiu, Annales Soc. Ent, France, vi, 9, 1837. 

 Isaura Joly, Annales des Scienc. Nat., ser. 2, XVII, 293, 1842. 



Carapace valves or shell oval, more or less globose, with a prominent 

 hinged back, Cyclas-like, with numerous lines of growth ; amber colored. 

 Body with 25-27 segments. Head with no "haft-organ ; " as a whole the 

 head is very large, being more like that of Limnetis than Limnadia, 

 having a long narrow rostrum forming a large proportion of the head ; 

 first antennse large and long, reaching nearly to the middle of the fla- 

 gella of the second pair; the latter with a stout multiarticulate scape, 

 the flagella extending well beyond the edge of the shell, and usually 

 composed of about 15-20 joints. Usually about 20 pairs of feet ; in the 

 female the coxal or maxilliform lobe is recurved, triangular, acute ; the 

 second and fourth eudites are small lobes of nearly equal size, while the 

 fifth is a loug, slender, narrow process, the sixth being like it, but either 

 wider and pointed at the end, or shorter than the fifth and scalloped 

 along the lower edge. Of the three exites, the gill is elongate, pear- 

 shaped, while the upper divisicm of the flabellum is very long and almost 

 filamental at the end, nearly reaching the upper side of the body, the 

 lower division being narrow, either x)ointed or rounded at the end, and 

 scalloped along the upper edge, closely resembling in form the sixth en- 

 dite. In the males the two anterior pairs are provided with hands, dif- 

 fering from those of the single first pair in Limnetis in the tubercle-like 

 fourth endite, armed with stifl", sharp spines, forming the comb, while the 

 finger-like fifth endite is somewhat bulbous at the end. 



The species of this ggnus may be recognized by the globose amber- 

 colored shell with numerous lines of growth. It diifers from Limnadia 

 in the large head, and long, large, acute beak, and in the lack of a haft- 

 organ, while it differs from Limnetis in the shell having lines of growth, 

 a distinct beak and hinge, while the rostrum is narrow and pointed, and 

 the number of body segments and legs is much greater, and the two 

 anterior pairs of feet in the male are provided with hands. Moreover, 

 the first antenncs are much larger, with indications of numerous joints. 



