Sept. 1899.] Dyar : Life- History of Cochlidion avellana. 205 



enlargement of these tubercles into spines and the alternation of the 

 subdorsal warts on the successive strong and weak segments. ^^ I do 

 not think that Dr. Chapman would have reached any other conclusion 

 if he had had as extensive a fauna in the family as is present in 

 America. The English species consist of only two members of the 

 paltearctic group without any of the others, and it is not surprising that 

 from these only he should have been misled, especially as the homology 

 of the tubercles of the Cochlidians is decidedly involved. 



Description of the Several Stages in Detail. 



£gg. — Elliptical, flat as usual, clear, translucent whitish with trans- 

 parent rim ; reticulations obscure ; size i.i x.8 x.i mm. Duration 

 six days. 



S/age I. (Plate V, Fig. i.) Head slightly testaceous, eye 

 black, mouth brown ; cervical shield blackish brown, covering the 

 head when it is retracted. Body thick, truncate before, narrowed and 

 rounded behind ; dorsal and lateral spaces moderate, flat ; subventral 

 space retracted. Tubercles large, round, the spines arranged as in 

 the other species of Cochlidion, the short limbs of the forked sub- 

 dorsals (joints 4 to 12) forming a short prominence on the shaft (Plate 

 V, Fig. 2) as in y-tnversa, not as long as in bigiittata. The subdorsals 

 of joints 5, 7, 9 and 11 lean outwardly. Spaces a little hollowed in- 

 tersegmentally both dorsally and laterally. Color whitish, after feed- 

 ing, becoming pale green from the blood, smooth, shining. Subdor- 

 sal ridge white, the lateral ridge less distinctly so ; setae pale with 

 dusky tips. The cervical shield pigment is less than in C. biguttata. 

 Length, i.o to 1.5 mm. 



Stage 11. (Plate V, Fig. 4) — Elliptical, truncate, narrowing 

 behind, widest through joints 4 and 5. Dorsal and lateral spaces 

 broad, narrowed at the ends, gradually so posteriorly ; sub -ventral 

 space retracted. Ridges prominent, with rounded tubercles, two long 

 black tipped setse on subdorsal ridge and at middle of joints 3 and 4, 

 one seta on the lateral ridge on joints 3 to 12, normal. Skin remotely 

 finely granular with pale secondary spines on the tubercles, the spines 

 bluntly tipped. The subdorsal setje still show some of the alternation 

 of stage I, those of joints 5, 7, 9 and 11 leaning outward, but all bear 

 two setfe. Pale green, subdorsal ridge whitish, a black shade under 

 joint 2 at the cervical shield. Length, 1.5 to 2.4 mm. 



* I owe the suggestion of strong and weak segments to Dr. Chapman's work on 

 Acronycta. 



