250 A.nnals Entomological Society of America [Vol. VI, 



vein it was found that this species comes in this respect midway 

 between sericata and sylvarum. In four cases the apical margin 

 of the first posterior cell was slightly shorter than the length 

 of the anterior cross vein, which is the typical condition in the 

 case of L. sericata. In the remaining twenty seven flies it 

 was about equal to the length of the anterior cross vein. Thus 

 for this species the character will not serve to differentiate 

 from the other two species. 



Having completed the resumes for the three species of 

 Lucilia the opportunity may be taken to make a few general 

 remarks on characters which have not been made use of in the 

 tables. 



First, as to size, there was found to be little difference in 

 the three species. Possibly caesar is generally somewhat 

 larger than the other two. In each species there is however 

 a considerable variation. To illustrate this it may be said 

 that in over 200 specimens of sericata the smallest fly was 5 

 mm. long and the largest 9 mm.; the average length was 

 from 7 to 8 mm. 



Then as to general color there was again a great range of 

 variation. Hough makes remark* that Tn all the Calliphor- 

 ineae of metallic color the shade varies through violet, green, 

 blue and copper color.' One' has only to look at a long series 

 of Lucilia to find that, in this genus at least, the remark holds 

 true. Generally, however, flies of L. sericata are brighter, 

 owing to a greater preponderance of the coppery color, then are 

 those of L. caesar and L. sylvarum.. 



Lastly a word may be said regarding the positions of the 

 dorsocentral and postacrostichal bristles both in relation to 

 the respective series separately and in relation to one another 

 As to the positions in their respective series it was found that 

 they were placed, almost without exception, in the same plane 

 longitudinally (cephalad-caudad) although there was variation. 

 Then as to the relative positions of the dorsocentrals and post- 

 acrostichals there was found to exist a considerable variation: 

 taking any four bristles transversely an imaginary line drawn 

 through their insertions usually approached a straight line; 

 this line was however scarcely ever absolutely straight and the 

 deviations from it did not follow any .definite plan. The 



*Synopsis of the Calliphorineag of the U. S., Zool. Bull., Vol. II, No. 6, Sept., 

 1899, p. 283. 



