Anatomy of the Male Genital Tube in Coleoptera. 587 



slender rod, the distal chitinisation being continued on to the 

 internal sac which is small, G. mutator is similar to this. 



Obs. — Geotrupes is very remarkable and distinct. The 

 tambour is very much closed, the basal portion of it is 

 greatly reduced in size and the diameter there is con- 

 siderably less than at the distal extremity, where the 

 shape is very peculiar. The lateral lobes are of unusual 

 form, and the distal chitinisation of the median lobe is 

 strange, though it differs a good deal according to the 

 species. Typhocus is not so extraordinary as the other 

 forms and may represent a distinct genus. 



Aclopus sp. 



Median lobe membranous. Lateral lobes long, thin and curved, 

 basal half connected together by membrane. Basal-piece tambour- 

 shape, much broader at base than at apex. The only specimen 

 of this form at our disposal is so much damaged that we can say 

 no more about it. 



Pachypus cornutus. 



Median lobe small, membranous; supported by a chitinous 

 patch on each side, prolonged into long median struts. Lateral 

 lobes fairly large, consolidated together for about one-third 

 from their base on the dorsal side, and on the ventral side with 

 membrane for about two-thirds from their base. Basal-piece large, 

 tambour- shape, slightly flattened and asymmetrical. Internal sac 

 large, covered with minute chitinous, pointed scales. 



Amphicoma vitlpes (PL XLIV fig. 14). 



Median lobe small, visible, membranous except at base, with two 

 median struts. Lateral lobes very small, free, their bases not 

 touching on dorsal or ventral side. Basal-piece forming a long, 

 thin, curved, chitinous tube, with basal opening at base on ventral 

 side. Internal sac well developed and complex. It is difficult to 

 distinguish the membranous median lobe from the sac as there is no 

 line of demarcation. 



The very long chitin tube formed in this insect by 

 the basal-piece is highly remarkable. In fig. 14 this part 

 is by a lapsus marked ml instead of bp ; but the position 

 of the median lobe is correctly indicated by the other ml 

 near the tip. 



