( 225 ) 



VIII. — Scottish National Antarctic Expedition : A Description of the Systematic 

 Anatomy of a Foetal Sea- Leopard (Stenorhynchus leptonyx), with Remarks upon 

 the Microscopical Anatomy of some of the Organs. By Harold Axel Haig, 

 M.B., B.S., M.R.C.S., late Lecturer in Histology and Embryology, University 

 College, Cardiff; M'Robert Research Fellow, University of Aberdeen. Com- 

 municated by Professor Arthur Robinson, M.D. 



(MS. received January 26, 1914. Read February 16, 1914. Issued separately April 30, 1914.) 



[Plates XIX.-XXIL] 



During the Scottish Antarctic Expedition of 1892-93 Dr W. S. Bruce secured 

 foetuses of Stenorhynchus leptonyx and Lobodon Carcinophaga, and on his return 

 passed them over, with other material, to Professor DArcy W. Thompson for the 

 Zoological Museum of University College, Dundee. While some of the material has 

 unfortunately been lost sight of during these twenty-one years, one specimen, viz. that 

 of a foetus of Stenorhynchus leptonyx, was still in existence, and was returned by 

 Professor D'Arcy Thompson to Dr Bruce, who in turn asked me to examine and 

 report upon it. Furthermore, during the voyage of the Scotia embryos of Leptony- 

 chotes weddelli were obtained by the Scotia naturalists, and these were passed on for 

 description to Professor Waterston, at that time in the University of Edinburgh. It 

 is on this material that the present monograph is based. 



Preliminary Considerations. 



The foetus of Stenoryhnchus leptonyx, which is in a good state of preservation, 

 measures 122 mm. from the tip of the tail to the most prominent part of the mid- 

 brain ; the greatest breadth is about 43 mm., and the greatest dorsi- ventral measure- 

 ment is in the mid-dorsal region, measurino; 35 mm. The umbilicus is situated 36 mm. 

 from the cloacal aperture, the umbilical cord being relatively short, owing to the 

 fact that the umbilical vessels soon undergo division into several large branches ; a 

 portion of the placenta with fragments of the foetal membranes is still attached 

 to the cord. The actual mode of placentation and the disposition of the foetal 

 membranes are points which will be discussed at a later stage (see infra, on the 

 Placenta). 



The skin is in many places thrown into folds, some of these being normal, but 



others undoubtedly due to shrinkage consequent upon the action of the preservative 



medium. The nippers are fully formed, nail rudiments being present upon the 



dorsal aspects of the distal phalanges. 



TRANS. ROY. SOC. EDIN., VOL. L. PART I. (NO. 8). 32 



