TUBERCLES OF LEPIDOPTEROUS LARVAE. 271 



Although the meso- and post-thoracic segments of the first larval 

 stage are usually duplicates — HepialidEe, Cossidse, Noctuse, Pyra- 

 lidae. Some evidence of the identity of iiB of thorax with iii b of 

 abdomen may be observed in Ehopalocera [Pieris, Terias) ; the 

 former is present on mesothorax, but absent, or minute, on 

 post-thorax ; while in Plutella (fig. 12) the fourth tubercle of the 

 mesothorax is normal, but marvellously reduced on the post- 

 thorax to a minute tubercle similar to iii b of abdomen, affording 

 what appears to be a complete gradation. 



I have attempted to show in the foregoing, that in the first 

 larval stage, above the line of spiracles, there are four separate 

 normal tubercles on the meso- and post-thoracic segments, which 

 are identical with three normal and one minute tubercles on the 

 abdominal segments — this is clearly shown in the illustrations 

 of Zeuzera * (figs. 7-8) larvae kindly sent me by Mr. Littler, of 

 Tasmania — and should be known by the same identification 

 numbers, thus i, ii, iii, iii b — the latter is necessary to prevent 

 confusion ; the two tubercles below the line of spiracles are un- 

 questionably iv and v. Usually, if not invariably, the anterior 

 subspiracular tubercles of both thorax and abdomen are higher 

 than the post-subspiracular in the first larval stage, curiously 

 in later stages among Noctuae (figs. 1-2) the posterior subspira- 

 cular is the highest. 



I commend anyone to a study of the Lyctenidae first larval 

 stage. It does not come within the scope of the present paper, 

 as the tubercles, though with single seta only, are more numer- 

 ous than our more usual and accepted primitive form ; but the 

 first abdominal segment has a tubercular arrangement like that 

 of the meso- and post-thoracic (Lampides), an alteration taking 

 place on second abdominal segment among the subspiracular 

 tubercles — clearly thoracic and abdominal tubercles are homo- 

 logous. 



Explanation of Plate IX. 



FIG. 



1. Melanchra mutaris, Second larval stage, mesothorax, x 80. 



(Identification numbers of tubercles,) 



2. M. viutans, Second stage, third abdominal segment, x 80. 



3. 4. ,, ,, ,, showing exact position of tubercles iii, 



iii B, iv, v, and spiracle, x 300, on post-thorax and first abdo- 

 minal segment. 



5. Porina despecta, First stage, mesothorax, x 200. 



6. ,, ,, ,, ,, third abdominal segment. 



6«. ,, ,, ,, ,, tubercles iii, iii b, iv, v, x 300. 



■■' The number and position of tubercles appear to be the important 

 characters; specialization of setae is apparently of no general value, and I 

 was in error in attaching importance to certain sette of Cossus {ante, p. 94), 

 as the setse of Zeuzera seem to be all that form. 



2a2 



