SKIAGRAPHIC RESEARCHES IN TERATOLOGY. 459 



Fis. 22, Plate X, shows the skeletal structure in a so-called siren foetus or 

 sympodia. It will be noted that the lower part of the vertebral column is im- 

 perfectly developed, that the pelvis is exceedingly rudimentary, being represented 

 by one small iliac bone, and that only one lower extremity is present. This contains 

 two bones, the upper of which represents the femur, and the lower the tibia. It will 

 further be noted that the radius is symmetrically absent in both arms. This last 

 abnormality is by no means an uncommon one, and is shown also in fig. 23 and 

 in fig. 24, Plate X, the latter being taken from a child aged eleven years. As 

 the pelvis and lower extremity in this case represent only one limb, the specimen 

 may be classed as an example of the variety known as monopodia. 



Group C. 

 {Characterised by the occurrence of determinants with inherent dejects.) 



Fig. 25, Plate XI, is taken from a foetus iniencephalus which was given to Dr 

 Ballantyne for examination by Professor Sir Alexander Simpson, to whom it was 

 sent with no clinical details. It is described in the Manual of Antenatal Pathology 

 (vol. ii, pp. 275, 276), where also its external appearances (fig. 44) and a sectional 

 view of the left slab (fig. 45) are figured. This monstrosity is so extreme that the 

 human form is lose, the head and trunk together making a more or less rounded 

 mass from which the limbs project. Through the extreme backward bending of 

 the head upon the trunk, the nape of the neck loses its external position. The three 

 factors in the production of iniencephaly are imperfect development of the occiput 

 in the neighbourhood of the foramen magnum, spina bifida of considerable extent, 

 and retroflexion of the trunk. 



The X-ray photograph supplements the frozen sectional view in respect to the 

 state of the lower jaw, the ribs, and the pelvis. The jaw is fairly well formed, the 

 ribs are much crowded together, the ossification of the lower half of the spine is 

 very irregular, and the pelvis is rudimentary. 



Fig. 26, Plate XI, represents an iniencephalic foetus which occurred in the practice 

 of Dr Murray Cairns of Liverpool in 1900. The labour was prolonged by reason 

 of the deformity. In this case the X-ray appearances which chiefly call for remark 

 are the acute flexure which is present at the upper end of the cervical spine, and 

 the sharp bend in the lumbar region. 



Fig. 27, Plate XII, is taken from a foetus with exomphalos and a congenital 



cutaneous band attaching the right wrist to the margin of the exomphalic aperture. 



It was born in the practice of Dr Maclagan of Sleaford in 1901, and it is figured 



and described in the second volume of the Manual of Antenatal Pathology (fig. 34, 



p. 180). The X-ray photograph shows the right arm in its attached position. 



Opposite the point where the exomphalos occurs there is an acute flexure of the 

 TRANS. ROY. SOU. EDIN., VOL. LI, PART II (NO. 10). 65 



