iyo E VOL UTION 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 mammae 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 mammae 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 mammae 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 mammae 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 



