48 FRANK R. LILLIE. 



maternal ovary ; the two chorions were entirely separate and there 

 was, therefore, no question of vascular anastomosis. 



Since this publication two additional cases have been received 

 (Nos. 63 and 64) similar in every respect to case 40. The 

 chorions were entirely separate in these cases also, and in each pair 

 both the male and female possessed normal reproductive organs. 

 In a third case, not previously reported (No. 93), in which the 

 female was also normal, the chorions were connected, but there was 

 no vascular union between the two sides. The notebook records 

 of these cases follow : 



No. 63. December 19, 1917; twins in uterus; mother's ovaries missing. 

 Uterus carefully opened ; the membranes appear at first sight to be fused 

 in the body of the uterus ; but they were really entirely separate, the 

 end of one being merely slightly invaginated over the other, so that 

 they fall apart intact. Length of male and female 22 cm. each ; repro- 

 ductive organs of both entirely normal. 



No. 64. February 1, 1918. Twins in uterus; both mother's ovaries present; 

 corpus luteum in each. Uterus carefully opened and chorions found to 

 be entirely separate. In this case the openings from the horns into the 

 body of the uterus were extremely constricted and the chorions were 

 confined to the horns. Male 14 cm. long; female 13.75 cm - long. Re- 

 productive organs of both entirely normal. 



No. 93. December 1, 1920. The twins were in the intact uterus; mother's 

 ovaries present ; a corpus luteum in each ovary. The chorions when 

 exposed were found to have a very narrow connection, which on ex- 

 amination turned out to be non-vascular. Length of male twin 10.25 

 cm., of female 9.75 cm. Reproductive organs of both entirely normal. 



Keller and Tandler (1916) report six cases, out of a total of 

 91 cases of two-sexed twins of cattle in which the foetal membranes 

 were examined, in which the female was normal. In one of these 

 the two chorions were adherent, but not fused in any way; in 

 another there was a narrow non-vascular strand uniting the two 

 chorions apparently similar to my case No. 93. In the remaining 

 four cases the chorions were well united, but the place of fusion 

 was indicated by a narrow strip of white, scar-like tissue com- 

 pletely encircling the chorion ; in three of these cases no vascular 

 anastomosis could be demonstrated across the place of fusion ; in 

 the fourth case several exceedingly small blood vessels crossed, 

 very different from the typical wide connection between the two 

 •circulations. The last case was in the fourth month of pregnancy 

 (size, of foetuses not given). The connections in question may 



