586 Mr. D. Sharp and Mr. F. Muir on the Comparative 
faces. Basal-piece large and curved, situated on ventral (?) side. 
Internal sac large and complex; surface covered with very short 
spines with a patch of dark hairs towards the base. 
A. simplicollis is very like A. laticollis but the sac bears 
a large curved chitinous plate near base, a patch of spine- 
like hairs about the middle and another near the apex, 
the rest of the surface covered with short spines. 
In Cloeotus, Millengenia, Anaides, Liparochrus, Hybosorus, 
and Geotrupes the lateral lobes are free, or only connected 
together at their bases. In Aphodius the lateral lobes 
have membranous extension along their edges but they 
are not amalgamated together. In the Coprinae the 
lateral lobes are connected together by membranes and 
form a more or less complete tube which includes the 
median lobe. 
Phaeochrous emarginatus (?) (Pl. XLV figs. 16 and 16a). 
Median lobe small but well chitinised ; median orifice on ventral 
side of tip ; median foramen large and basally placed. Lateral lobes 
asymmetrical, the right shorter and broader than the other, concave on 
inner side at base for the reception of the median lobe ; left curved, 
with projection near base on dorsal edge. Basal-piece large, form- 
ing a chitinous tube with a large opening on the ventro-basal part. 
Internal sac small and simple, covered with brown hair. When at 
rest the aedeagus lies on its side. 
Typhoeus typhoeus (Pl. XLV figs. 17 and 17a). 
Median lobe reduced to a small chitin ring (ml) projecting into the 
basal-piece as two median struts (ms). Lateral lobes small, but 
entirely concealing the median lobe. Basal-piece large, forming 
a chitinous lobe, bent downward near the base, the basal opening 
large, somewhat dorsal and the edges asymmetrical; the apical 
ventral margin (a) is produced beyond, and conceals, the base of 
the lateral lobes. Internal sac small, covered with brown hairs. 
Geotrupes pyrenaeus, var. from Reynosa ; is of the same type as 
Typhoeus but the ventral apical margin is produced as two broad 
plates which cover the ventral side of the lateral lobes. 
In G. stercorarius, also the ventral distal edge of the basal-piece is 
produced into two spatulate lobes which cover the ventral side of 
the lateral lobe and the dorsal edge is produced into two broad lobes 
which cover the dorsal surface of the lateral lobes. The lateral 
lobes are small and asymmetrical. The median lobe is reduced to a 
membrane supported by the median struts consolidated into one 
