178 MR. LUBBOCK ON THE CUTANEOUS MUSCLES 
different species would throw much light upon this question, but I have not at present 
the materials necessary for the investigation. 
Nos. 2 and 3 are 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 passes 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 bind 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 passing straight forward as in the abdominal segments, 
inclines to the ventral side in front. Both branches rise at about the middle line of the 
front 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 this segment. 
No. 16 is almost entirely covered by 17. 
No. 18, instead of being parallel to 16 and 17, as in the abdominal — 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 margin 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 
downward, is attached to the skin under the fore end of 21. 
No. 28 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 which 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 line. à 
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 first abdominal segment, but lies under instead of over 5 
and 55. 
No. 35 is as in the abdominal segment. 
