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74
M. BOWNES
x
(c)
(b)
(a)
MH
MH,
•MT
Fig. 11. (a) Class 1. Abnormal embryo. This shows partial deletion of rows of
chaetae (Cti) and abnormal fusions of the segment.
(b) Class 1. Abnormal fusions of segments and a case where half an abdominal
segment is linked to half a thoracic segment (x).
(c) Class 1. Rows of chaetae radiate out from one point near the posterior of the
embryo.
(d) Class 2. There is a patch of undifferentiated tissue at the posterior and extended
Malpighian tubules (MT). The segments are crowded into the anterior half of the
egg.
(e) Class 3. There is yolk at the anterior of the embryo. Segments are crowded into
the posterior two-thirds of the egg. Abnormal parts of the mouthhook apparatus
are present (MH).
(/) Class 6. Half an embryo has formed along one side of the egg. There is only one
mouthhook. To the other side is a mass of undifferentiated tissue.