liEPRODUCTIVE CVOEE IN DASYUKdS VIVERIilNUS. 137 
Tlie ridges around tlie posterior pair of teats are continuous 
in the middle line, whereas those at the anterior end are 
separated from one another by a considerable interval. There 
is also a space between the median walls of the ridges of the 
middle pair of teats, so that the three pairs are approximately 
arranged in the form of a horse-shoe with the open end 
situated anteriorly (see Text-fig. 1, a). The floor of the pouch 
between the ridges surrounding the teats is loose and folded 
and frequently falls into a raised fold along the middle line. 
The number of teats is subject to slight variation ; thus in 
Text-fig. 1. 
Diagram to show the aiTangemeiit of the teats witliin the pouch, 
(a) in the normal female with six teats; (b) in the females with 
eight teats, t. Teat. L. Ledge surrounding teat. d. Depres- 
sion, R. Raised ridge, f. Floor of pouch, w. Pouch -wall. 
over 170 females examined one pouch contained five teats, 
two pouches contained seven teats and five contained eight 
teats\ but all the remainder had the normal number— six. 
According to Bresslau (4, p. 672 et seq.) the mammary 
(nipple) primordia take their origin in Dasyurus as in other 
Marsupials from a pair of laterally situated primary anlagen, 
each consisting of an epidermal thickening and an underlying 
area of condensed cutis. As a rule, three pairs of mammary 
primordia are formed, three from each primary aiilage, but 
^ Khitsch (quoted by Bresslau (4)) also records the occurrence of 8 teats 
in one individual. 
