StaphylinidcB of the Amazon Valley. 125 



■width ; just a little broader in front, and the sides a little 

 sinuate ; on each side of the middle is an irregular line of 

 about nine jDunctures, and other punctures are scattered 

 along the sides, es]iecially near the front part. Elytra 

 about the length of the thorax, blue, Avith a grey pubes- 

 cence at the base and near the extremity, moderately 

 closely punctured. Hind body yellow, Avith the 2nd seg- 

 ment darker ; it is almost impunctate, and very sparingly 

 pubescent above, beneath distinctly but rather sparingly 

 punctured, and Avith a fine long pubescence. Legs yelloAA^, 

 Avith the coxa3 pitchy. 



The chai-acters of the male are A^ery complicated and 

 most remarkable. The front tibiae are dilated towards 

 the apex, and somcAvhat concave on the inner side; the 

 three basal joints of the front tarsi are a little dilated. The 

 dorsal plate of the 7 th segment of the hind body has three 

 sinuses at the hind margin ; the middle one is the broader, 

 but is not formed by the margin being cut aAvay, but by 

 its being turned doAvnAvards ; at the base of this turned- 

 doAvn portion are tAvo sharp teeth, placed near to one 

 another ; from the extremity of this turued-doAATi part pro- 

 ject tAvo vertical processes. The ventral plate of the same 

 segment is a little produced, and has a deep incision or 

 notch in the hind margin ; along each side of this notch it 

 is broadly impressed. The lateral lobes of the 8th seg- 

 ment are modified in a most extraordinary manner ; each 

 terminates in three processes, — a broad, truncate, central 

 one, armed on the inner side Avith tAvo roAvs of file-like 

 asperities, and a long, slender, somcAvhat curved process 

 on each side. The body of the ^edeagus terminates in 

 a produced point or beak, and is furnished beneath 

 Avith a Hgula longer and broader than the beak, and 

 densely set A\dth black asperities on each side, towards 

 the end. 



Ega ; tAvo males. 



Obs. — This species is undoubtedly closely allied to 

 St. venustus, Er., from Cayenne, but I cannot make the <J 

 characters agree Avith Erichson's description. These male 

 characters are the most extraordinary I have met Avith 

 in any Coleopterous insect. 



Xanthopygus. 



This genus, like the tAvo preceding ones, is due to 

 Dr. Kraatz ; but unlike them, it seems to be composed of 



