Anatomy of the Male Genital Tube in Coleoptera. 493 
and Cicindelidae. In the latter two families the median 
lobe is a more or less perfect tube with the median orifice 
at or near the distal end, and the median foramen at the 
basal end; in the three other families it forms a chitinous 
organ, grooved along the ventral surface (or the lateral 
margin turned down), with a membranous tongue cover- 
ing the basal part of the groove. There being no differ- 
entiated sac it is impossible to say how much of the 
ejaculatory duct is evaginated during coition.* 
Unfortunately the only Amphizoidae we could procure 
were females. 
Family GYRINIDAE. 
Forms examined: Hnhydrus sp. n., aff. #. atrati, Lita, 
4000 ft. Gyrinus natator and urinator, England. Orecto- 
chilus dispar Walker, Ceylon. 
Figs. 42, 48 and 43a Pl. XLIX. 
Gyrinus natator (Pl. XLIX fig. 42). 
Median lobe slightly flattened and curved; tip truncate ; dorsal 
and lateral parts chitinous ; median orifice forming a narrow slit on 
the membranous ventral side near tip; median foramen at base. 
Lateral lobes flattened horizontally, narrow at base and gradually 
widening to truncate apex, which bears long hairs; consolidated 
along ventral basal half and near base on dorsal side. Median lobe 
articulated to base of lateral lobes on dorsal side. Basal-piece large, 
forming a large chitinous plate on ventral and lateral sides ; mem- 
branous on dorsal side; membrane connecting it to lateral lobes 
large and allowing great movements of parts. No differentiated 
internal sac. 
Enhydrus, sp. 
This is the same type as G. natator, the median lobe being 
pointed and the lateral lobes pointed on the inner side of a widened 
tip. Basal-piece large, but connecting membrane not so large as in 
G. natator, and not allowing so much movement between basal-piece 
and lateral lobes. No differentiated internal sac. 
Oretochilus dispar (Pl. XLIX figs. 43 and 43a). 
Median lobe tubular, drawn to a point on the ventral side of the 
apex ; median orifice situated on dorsal side of apex; median fora- 
* F. Netolitzky (Deut. Ent. Zeitschr., 1911, p. 271) has discussed 
the Adephaga from the point of view of the lateral lobes. 
TRANS. ENT. SOC. LOND. 1912.—PART III. (DEC.) LL 
