86 PROCEEDINGS OF THE NATIONAL, MUSEUM. vol. CO 



Internal genennc characters. — The esophagus is inclined forward 

 at an angle of 45° and enters the extreme anterior end of the stomach. 

 The latter is enlarged only a little, and passes into a wide intestine 

 which runs the entire length of the body and is contracted into a 

 short rectum. 



The ovaries are situated on either side of the intestine near the 

 dorsal surface of the first thorax segment. The oviducts, starting 

 from the anterior ends of the ovaries, curve downward, outward, and 

 backward along the sides of the thorax to the vulvae. When fully 

 developed they fill nearly the entire space between the intestine 

 and the body wall. The eggs are scattered loosely through the ovi- 

 ducts, are not arranged in any definite order, and are not flattened. 

 The sperm receptacle is just inside the ventral body wall and is ob- 

 long, with rounded ends. 



In the male the testes and sperm ducts are arranged similarly with 

 the spermatophore receptacle near the posterior end of the genital 

 segment. 



In the female the cement glands lie on either side of the intestine, 

 ventral to the oviducts, and are confined to the genital segment. They 

 are about the same diameter throughout their anterior half, which is 

 glandular and not segmented, while the posterior half is much nar- 

 rowed. 



From the supraesophageal ganglion branches go to the two pairs 

 of antennae and the front of the head ; from the inf raesophageal 

 ganglion similar branches go to the various mouth parts and the first 

 swimming legs. A ventral trunk runs back through the thorax to 

 the anterior end of the fifth segment, where it divides into two 

 branches, which separate a little and reach the posterior end of the 

 genital segment. On either side of the intestine in each segment pos- 

 terior to the first is a band of dorsoventral muscles which aid in the 

 extrusion of the eggs. 



Type of the genus. — Bichelesthium oblonguni (Abildgaard), mon- 

 otypic. 



DICHELESTHIUM OBLONGUM ( AbUdgaard) . 



Plate 13, fig. 105. 

 Galipiis ohlongns ABtLDGAARD, Skrivter af Naturhistorie Selskabet, vol. 3, 



1794, p. 52, pi. 5, figs. 4-11. 

 Dichclestiwm stviHonis Hermann, M^moire Apterologique, 1S04, p. 125, p!. 5, 



figs. 7-8. 

 DichelestMum sturionis Desmakest, Considerations generales sur la Classe 



des Crustaces. 1825, p. 337, pi. 50, fig. 6. 

 DicJielestium sturionis Lateeille, Regne Animal de Cuvier, 1817, vol. 3, 



p. 66; Families naturelles du Regne Animal, 1825, p. .306; Cours d'Ento- 



mologie, 1831, p. 455. 

 Dichelestiiim sturionis Bosc, Historie Naturelle des Crustac6s, 1830, vol. 



2, p. 223, pi. 18, b, fig. 2. 

 Dichelesthium sturionis Nordmann, Mikrographisclie Beitrage, 1832, p. 41. 



