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170 EVOLUTION AND DISEASE. 
of a cow which had two rudimentary teats in addition to 
the normal four. In consequence of an injury one of 
the normal teats became obstructed ; this accident was 
compensated, as one of the accessory teats enlarged and 
was regularly milked. A female zebu (Bos indicus) at 
the Zoological Gardens has an extra well-formed teat on 
the right side. Goats and sheep are normally furnished 
with two teats, but it is not unusual to find a rudimentary - 
pair posterior, and occasionally anterior, to the normal 
teats. 
We may now consider supernumerary mamme occur- 
ring in the line of the deep epigastric artery which are 
not atavistic. In the human female, and occasionally in 
the cow, we find mammary glands with bifid nipples ; in 
other cases we find two mamme coalesced, but each has 
a separate teat. These conditions are not reversions, 
but arise by dichotomy from a single gland germ. 
Intermediate stages between bifid nipples and two 
separate mamme have been recorded. 
Aberrant mammary glands, or those arising as spon- 
taneous variations, claim careful consideration, for they 
may arise on any cutaneous surface which is rich in 
sebaceous glands: as a rule they are furnished with 
nipples, but not constantly. Among the rarer positions 
for such aberrant mamme are the thigh, shoulder, and 
cheek. The oft-quoted case of a functional mamma on 
the thigh rests upon the authority of a committee of the 
French Academy of Sciences. Barth recently gave an 
account of a rudimentary mamma connected with the 
skin on the cheek of a maiden aged twenty years, it 
was situated immediately in front of the right ear, and 
