NEW SOUTH AFRICAN ARACHNIDA. 327 



keilandsi.^ It resembles that form also in the posterior 

 position of the median eyes ; it differs in that the tail of the 

 male is much stouter in natal en sis. The fifth caudal 

 segment in an adult male of keilandsi measures 10*5 mm. in 

 length and 3'75 mm. in width. 



Dr. Purcell " points out in his important monograph on the 

 genus Opisthophthalmus that the presence or absence of 

 stridu-latory lamellee on the chelicerge is usually of no specific 

 value. However, I am inclined to regard the character of 

 some importance in the various forms which range around and 

 between pugnax and latimanus. Such lamellas are 

 present in all our examples of latimanus, 132 specimens of 

 all sizes, from Grahamstown, Highlands, Brakkloof, Fort 

 Beaufort, Jansenville, Schurfteberg, Alicedale, Cllen Lynden, 

 Mimosa, Redhouse, Alexandria, and Queenstown ; they are 

 even present as a row of bristles on the newly hatched young. 

 They are present in latimanus var. austeroides mihi and 

 in every specimen of our series of typical pugnax; they are 

 completely absent in keilandsi. 



It is not impi'obable that intermediates between keilandsi 

 and natal en sis will be found, in which case it will no longer 

 be possible to maintain pugnax as a species distinct from 

 latimanus. With the discovery of new local forms in the 

 genus Opisthophthalmus the difi^erences between the so- 

 called species ai'e gradually breaking down and the genus is 

 seen to be composed of numerous local forms which more or 

 less completely grade into each other. 



' ' Records, Albany Musextm,' vol. iii, p. 7, 1914. 

 - ' Annals S. Af r. Museum,' vol. i, p. 134, 1899. 



