1891.] ON BUTTERFLIES FROM SOUTH-WESTERN AFRICA. 59 



Figs. 4 & 5. Lateral and dorsal views respectively of left valve of small adult 

 Unio, showing the notches, x, produced on each line of growth by 

 the previous constriction caused by the shell-teeth of the Glochidium- 

 shell. 



Fig. 6. DiagTam to show the dii'ection of ciliary currents on external surface of 

 nephridium. 



7. Diagram to show valvular action of ventral edge of mantle-flaps. 



a, a', right and left valves of shell ; b, b', right and left mantle-folds ; 



c, c', thickened margins of b, b' ; d, d', lines of attachment of b, b' to 

 a, a'. The arrows indicate the direction of water-pressure. 



8. Diagram of relation of gill-lamellffi to show how the ova are prevented 



from falling into the internal gill, a, visceral mass ; c, mantle-flap ; 



d, axis of gill ; e, inner, er, outer lamella of external gill-plate ; 

 f, outer, fr, inner lamella of internal gill-plate ; ff, line of con- 

 crescence ; i, suprabranchial space of subpallial chamber. 



3. On Butterflies collected in Tropical South-western Africa 

 by Mr. A. W. Eriksson. By Roland Trimen, F.E.S., 

 &c.^ Curator of the South-African Museum^ Cape 



Town. 



[Eeceived December 8, 1890.] 



(Plates Vni. & IX.) 



Well known for Ms many years' experience as explorer and hunter 

 in the tropical Interior, and for the zeal and success with which he 

 has collected and observed the ornithological fauna, Mr. Axel W. 

 Eriksson has latterly, at my instance, turned his attention to the 

 insects inhabiting the less known tracts. The collection of which 

 the Butterflies now under notice formed the larger part was made 

 by him during six months — 1st August, 1887, to 25th January, 

 1888 — spent in travelling between Ehanda, in the Southern Ombuela 

 (or Ambuella) country, and Omborombongo, in Central Damara- 

 land. 



The country traversed may be said in general terms to be bounded, 

 except to the South-west, by the rivers Cunene, Okavango, and 

 Omaramba-Oamatako, and it extends from North to South over 

 about five and a half degrees of latitude (15° 15' to 20° 45' S.), and 

 from West to East almost the same of longitude (15° to 21° 20' E.). 

 The route pursued and the time spent in each locality appear from 

 Mr. Eriksson's notes to have been as follows, viz. : — Omrora, " be- 

 tween Ovaquenyama and Ombuela," 1st to 25th August; Ehanda, 

 26th August to 30th September; Humbe, Cunene River, October; 

 Omrora again, November; Otiembora, 20th November to 3rd De- 

 cember ; the course of the Okavango River, "between the tributaries 

 Omaramba-Caronga and Omaramba-Oamatako," December ; the 

 course of the Omaramba-Oamatako, " between its junction with the 

 Okavango and Otjitoe," 2nd to 14th January, 1888 ; and the course 

 of the same river, " between Otjitoe nnd Omborombongo," 15th to 

 25th January. This route is remote from the sea-coast, never 



