298 



BUT.T.ETIN OF THE BUKEAU OF FISHERIES. 



to the ventral surface. This arrangement of the eyes and penetration of the pigment is the same in the 

 two species here described, and in the Acilius larva, which follows, but nothing like it was noted in 

 any of the other larvae. It thus serves to denote the close relationship of this genus with Acilius. 



Pupation. — ^This larva does not travel as far from the water's edge as the preceding but builds out 

 of mud pellets a similar pupal chamber, which is ellipsoidal and about 14 by 16 mm., outside measure. 

 This is often built beside a grass or rush stem or under a pile of rubbish and its walls are so thin that the 

 larva often tears them asunder by snapping about when disturbed. Since the inner diameter of the 

 chamber is only a trifle more than half the length of the larva, the latter is of necessity folded upon 

 itself, like the species already described. Similarly the skin splits open along the dorsal mid line from 

 the base of the head to the seventh abdominal segment and is flattened against the inside of the chamber 

 WfiU. About 30 hours elapse between the completion of the chamber and pupation. 



Description of the pupa. — This pupa differs from the preceding in the following particulars. In size 

 it is half as large again, measuring 13 to 14 mm. in length and 6 to 7 mm. in greatest width. The front 

 margin of the prothorax is armed with a row of short spines rather than long styli and there are no proc- 

 esses on its lateral margins. The antennae are longer and reach nearly to the tips of the wings. The 

 first and second legs are not as long, and the latter do not reach the tips of the elytra; the third legs are 

 the same length, but all three pairs are much stouter. The length of time spent in the pupal stage varies 

 considerably as can be seen from the following table compiled from eight larvae reared to the adult stage. 



Completion of chamber. 



Pupation. 



Emergence. 



Completion of chamber. 



Pupation. 



Emergence. 



Aug. 3 





Aug. 8. 

 Aug. 9. 



Aug. 7. 







Aug. 8. 

 Aug. 10. 





.^."lo*::;::::::::::::: 



Do 





Do 



....do 



Do 



.^."io'.v.::;::::::::::: 



Do. 

 Aug. 11. 



Do 



Aug. 3 















Description of the adult. — This beetle may be distinguished from the preceding species by the fol- 

 lowing differences: In size it averages fully one-half longer and one-third wider, having a length of 15 

 to 16 mm. and a width of 8 to 8.5 mm. In color the sides of the M -shaped mark on the head do not 

 touch the eyes, but there is a distinct yellow band between the two, whereas in the preceding species 

 they do touch the eyes and there is no band. On the thorax of basilaris the two transverse black bands 

 touch the anterior and posterior margins, respectively, and there is a single yellow band between them. 

 In ornaticollis they do not touch these margins and there are three yellow bands. Across the bases 

 of the elytra in the preceding species is a black band, which turns backward a short distance at the 

 outer corners; in the present species the bases are yellow, and this color extends along the inner margins 

 nearly or quite to the posterior ends. In ornaticollis the distal half of the lateral margins of the elytra is 

 heavily fringed with long hairs, in basilaris it is nearly smooth. The rounded tooth at the dorsal corner 

 of the mandibles of the preceding species is bordered on either side by a deep sinus; in the present 

 species there are no sinuses. The labium here is relatively shorter and wider; in the preceding species 

 it is longer and narrower. In the dilated tarsus of the male of this species the basal joint is longer than 

 the second and third joints together, and carries 10 disks, 2 large ones on the proximal and 1 on the 

 distal margin, the 3 about the same size and forming a triangle, the other disks much smaller and 

 unequal on the lateral and distal margins. The second joint carries 5 on the inner and 2 on the outer 

 margin; the third joint carries 10 irregularly arranged, 5 of medium size and 5 smaller ones. In the 

 preceding species the basal joint is also longer than the second and third joints together, but it carries 

 only 8 disks, 1 large one at the outer proximal corner, 1 half as large at the inner proximal comer, 

 another the same size on the distal margin, and 5 much smaller ones along the outer distal area. The 

 second and third joints each carry 6 disks about the size of the smallest ones on the basal joint along 

 the inner and distal margins. 



These differences in the adult beetles, together with the life histories here presented, efectively 

 establish the present as a distinct species rather than a variety of basilaris. Blatchley (1919) arrived at 

 the same decision from his study of the adults in opposition to Leng and Mutchler (1918, p. 90), who 

 considered ornaticollis as a mere variety of basilaris. 



