Anatomy of the Male Genital Tube in Coleoptera. 531 
The tegmen of this comes near to the Trogositidae, but 
the median lobe is quite unique so far as we have 
observed. 
Family GEORYSSIDAE. 
Form examined: Georyssus pygmaeus Fabr., England. 
Fig. 124 Pl. LXII. 
G. pygmaeus (Pl. LXIT fig. 124). 
Trilobe form, flattened horizontally. Median lobe flattened, 
pointed at tip. Lateral lobes flattened, rounded at apex, concave 
along the inner edge so that the median lobe can fit into the con- 
cavity, and so become nearly hidden. Basal-piece large, chitinous 
on ventral face, membranous on dorsal. Sac not examined. 
This is a trilobe form, and reminds one of some of the 
Gyrinidae. It cannot be placed with Cyathocerus. 
Family HETEROCERIDAE. 
Form examined: Heterocerus flecuosus Steph., England. 
Figs. 125 and 125a@ Pl. LXIIL. 
H, flexuosus (figs. 125, 125a). 
Median lobe large, chitinous on ventral and lateral faces, mem- 
branous on dorsal, produced into short bilobe strut (ms) at base, the 
apical point slightly turned aside. The internal sac appears to 
be permanently everted and, when at rest, twisted up on the dorsal 
face of the median lobe. Tegmen forming a large cap on dorsal 
aspect of median lobe, produced into a broad strut at base, slightly 
emarginate at apex, and the lateral edges turned down and envelop- 
ing the side of the median lobe, but only connected by membrane 
(m) on the ventral aspect. 
Family PARNIDAE (= Dryopidae of some). 
Forms examined: Pelonomus palpalis Sh., Central 
America. Parnus luwridus and other species, England. 
Figs. 126 and 127 Pl. LXIII. 
P. palpalis (Pl. LXIIT fig. 126). 
Median lobe long, slender and slightly curved, the median 
orifice on ventral aspect near tip, base articulated to base of lateral 
lobe on dorsal aspect (pa). Lateral lobes large, pointed at tips, 
