178 MR. LUBBOCK ON THE CUTANEOUS MUSCLES 



different species wovild tlii'ow mucli light upou this question, but I liave not at present 

 the materials necessarj^ for the investigation. 



Nos. 2 and 3 ai'e entirely absent. 



No. 4 passes straight forward, but does not reach the front of the segment. 



No. 5 is completely double. One branch rises at the side of 1, and passes diagonally 

 forward and upward to be inserted under it. The other rises under the lower side of 1, 

 and jjasses forward parallel with the other branch, to be inserted under its upper part. 



No. 6 rises on the same transverse line and a little on the ventral side of 1, and passes 

 back near the hind end of the segment, inclining at the same time downward. 



No. 7 lies under or sometimes at the ventral side of, and more or less parallel to, the 

 preceding. 



No. 8 is double, and instead of passrag straight forward as in the abdominal segments, 

 inclines to the ventral side in front. Both branches rise at about the middle line of the 

 fi'ont of the segment, and diverge gradually. The one is inserted under the hinder end 

 of 1, and the other under and at the side of the lower branch of 5. 



No. 9 rises under the posterior ends of No. 5', and passes forward and upward, almost 

 to the middle line of the back and for three-fourths of the length of the segment. 



Nos. 10 and 11 have coalesced in tliis segment. 



No. 16 is almost eutii-ely covered by 17. 



No. 18, instead of being parallel to 16 and 17, as in the abdominal muscles, rises under 

 the posterior end of 17, and passing forward and downward, crosses the middle line of 

 the segment between the two nervous chords, which are here at some distance from one 

 another, and is attached to the fore margui of the segment on the ventral side of No. 21. 



Nos. 19 and 20 lie under 17 and 21. 



No. 21 rises on the fore margin of the segment and at the ventral side of 17, and 

 passes back, under 18, to the same transverse line as 16 and 17. 



No. 22 rises on the posterior margin of the segment under 16, and passing forward and 

 doAvnward, is attached to the skin iinder the fore end of 21. 



No. 23 rises under the posterior end of 21, and passes forward and upward to the fore 

 end of 17, where it is inserted. 



Nos. 24 and 25 are attached in front as usual, but instead of extending the whole 

 length of the segment to wliich they belong, are attached to the middle line of the ventral 

 side, and are not above half the usual length. 



No. 26 rises close to the ventral chord not very far from the posterior end of the seg- 

 ment, and passes forward and upward to be attached under the fore end of 20. 



No. 27 is entirely absent. 



No. 28 rises on the dorsal side of 30 and under 20, and passes forward parallel to 30 and 

 under 26 to the middle ventral liae. 



No. 30 rises under 23, and passes downward and forward to the posterior end of 26. 



Nos. 29, 31, 32 and 33 are altogether absent. 



No. 34 is almost as in the fii'st abdominal segment, but lies under instead of over 54 

 and 55. 



No. 35 is as in the abdominal segment. 



