134 THE BONES. 



that section of obstetrics dealing with the diameters of the pelvis. These may 

 be determined in several ways, which, in veterinary surgery, daily receive the 

 sanction of experience. 



Some years ago we indicated one,^ which consists in measuring the horizontal 

 distances between the two haimches and the two ischiatic tuberosities, and the 

 vertical distance extending from the coxo-femoral articulation to the most 

 salient part of the croup ; then to take a fourth of the total of the two first 

 measurements, in order to obtain the transverse diameter of the inlet, and 

 three-fourths of the third, to have the vertical diameter of this opening. 



Saint-Cyr and Violet have investigated the relation existing between the 

 height of the Mare and the vertical diameter of the pelvis, then that of the 

 width of the croup to the bis-iliac diameter ; and they have found that the first 

 was equal to 0"1515 centimetres ; the second to 0'4654, in a well-bred Mare, to 

 0*3945 in common-bred Mares. Consequently, according to the pelvimetric 

 procedure of these authorities, it is sufficient to multiply the height of the Mare 

 by 0-1515 to have the vertical diameter of the inlet, and the width of the croup 

 by 0*4654 or 0"3945, according to circumstances, to find the transverse diameter. 

 But this question rather appertains to obstetrics.^ 



2. Differences in the Pelvis of the Sexes. — The pelvis of the Mare 

 exceeds that of the Horse in all its dimensions, but the difference is most, 

 marked in the transverse diameters (Figs. 86, 87). 



The inlet forms a vast circumference, when compared with that of the male ; 

 the pectineal crests are wide apart, and the distance separating the anterior 

 border of the pubis from the lower face of the sacrum is considerable. 



If the pelvis be viewed in its superior plane, it is found that in the Mare the 

 ischiatic notches are very deep ; that the internal border of the ilium forms a 

 regularly curved and very concave line ; and that the supra-cotyloid crests, or 

 ischiatic spines, are widely separated from each other. It is also noticed that 

 the floor of the pelvis is wide, and that the bones composing it tend towards the 

 same horizontal Hne. 



In the male, the ischiatic border is only represented by a very curved line ; 

 this line is composed of two almost straight portions, which join at an obtuse 

 angle at the origin of the neck of the ilium ; the supra-cotyloid crests are 

 relatively near each other, and bent towards the longitudinal axis ; while the 

 two moieties of the pelvic floor are directed very obliquely downwards and 

 inwards. 



In the Mare, the ischial arch is larger than in the male, and forms a regular 

 curve uniting the two tuberosities of the same name. In the Horse, the two 

 ischial tuberosities are but little apart, and the ischial arch forms a somewhat 

 acute angle, with its borders nearly straight. 



Lastly, when the pelvis is examined in its inferior plane, in addition to the 

 features already indicated in the ischial arch, it is found that in the Mare the 

 obturator foramina are large and nearly circular, while in the Horse they are 

 elliptical ; the cotyloid cavities are also further removed from the ischio-pubic 

 symphysis in the female than in the male. 



The sacrum of the Mare has appeared to us, in some individuals to be a little 

 more arched from before to behind than that of the Horse ; but this character 

 is not constant. 



' Arloing;, Journal Vet^rinaire de Lyon. 1868. 



= Saint Cyr and Violet, Trait€ cV Ohstetrique VitMnaire, Paris: 1888. 



