WERNER MARCHAND 137 



The pigment is, according to Lecaillon, not altered by alcohol, 

 while in eggs in which the color is due to the yolk the latter is usually 

 decolorized by the action of alcohol. 



The female constructs its egg mass, depositing the eggs one after 

 the other, beginning at the anterior end. At last, when the mass 

 has reached a certain width the eggs are found arranged in horizontal 

 and more or less regular layers, while the lower border of the mass 

 forms a pronounced projection, the beginning of the depression of 

 the lower surface. While the female is sitting with head turned 

 downwards the tip of the abdomen is placed upwards, towards the 

 point where the egg is to be laid. 



The eggs themselves are of curved shape, they measure about 2.5 

 mm. in length and only 0.5 mm. in width. Their convex side, which 

 is chiefly visible in those which lie at the periphery of the egg mass, 

 is always directed towards the outer side of the latter. 



Lecaillon calls attention to the significant regularity of tabanid egg 

 masses. Among the greater part of insects which deposit their eggs 

 freely on leaves, twigs, walls, etc., the egg mass consists generally of 

 an agglomeration of any shape which it may assume under the con- 

 ditions presented by the object on which the eggs are laid. In 

 Tahanus quatuornotatus , however, the case is different; the egg mass 

 has a very complicated structure, which to a great extent is inde- 

 pendent of the shape of the supporting object, and of a strictly bi- 

 lateral symmetry which can certainly be regarded as a characteristic 

 of evolutionary perfection. From Hart's figures it is seen that the 

 same character is found also in the egg mass of Tahanus atratus and 

 Chrysops ccstuans (mcerens); and it is probably generally found 

 among tabanids. 



In a later paper, in 1911, Lecaillon reports additional observations 

 made on this species in 1906, 1907, and 1908, on the conditions un- 

 der which the eggs are laid, and a more amplified description of the 

 egg masses themselves. 



Since the first publication, a considerable number of egg masses of 

 Tahanus quatuornotatus were examined and a number of individual dif- 

 ferences were found in the arrangement of the egg masses. Some of 

 the more interesting forms met with were figured in the plate added 

 to the second publication. The egg mass previously described is 



