90 SHOULDER-GIRDLE AND BREAST-BONE. 



EEPTILIA. 



In describing the structure of the Sternum and Shoulder-girdle of the true Saurians, I shall 

 enrich my paper by inserting a translation (by Mr. Power) of the late Dr. Heinrich Rathke's 

 small but most invaluable work upon the Sternum in this Class. 1 



RATHKE, ' Ueber den Bau und die Entwickelung des Brustbeins der Saurier,' pp. 1 7. 4to, 



Konigsberg, 1853. 



1. A Shoulder-girdle and a Sternum have hitherto been unacknowledged by anatomists and 

 physiologists in several of those species of Saurians whose form resembles that of Snakes, and which 

 were formerly on this account actually enumerated amongst the Snakes ; but from my investigations 

 it may reasonably be concluded that the bony girdle of the Shoulder is present in all the Snake-like 

 Saurians, and that the Sternum only fails entirely in the footless Saurii Annulati. 



2. In three species of the small group of Saurii Annulati, namely, in Amphisbeena fuliginosa, 

 Amphisbeena alba, and Lepidosternon micro cephalum, I found between the lingual bone and the most ante- 

 rior ribs, but much nearer to the latter than to the former, a pair of small bones, which may be con- 

 sidered as the rudiments of a Shoulder-girdle [cor aco -scapula?]. In Amphisbeena fuliginosa, where its 

 dark brown colour, which is common to it and to the other bones of the skeleton, first led me to 

 remark them, they form cylinders, the length of which was only one line (one twelfth of an inch), 

 and the thickness only one eighth of a line, even in the largest of four specimens, the length of which 

 was thirteen and a half inches. Their direction, when the animal was placed on its belly, was some- 

 what oblique from above downwards and inwards. 



In a specimen of Amphisbeena alba, whose length was one foot six inches six lines, they were also 

 only one line long, but proportionately somewhat thicker than in the former species. They also did 

 not possess a regular cylindrical form, but were somewhat thinner in the middle than at their rounded 

 ends, the transverse diameter of which amounted to one sixth of a line. Their colour, like that of 

 the remainder of the skeleton, was white, and their direction, like that of the preceding species, nearly 

 perpendicular. In a Lepidosternon microcephalum having a length of one foot nine inches six lines 

 the rudiments of the Shoulder-girdle [coraco-scapulce] had the form of beans, [though somewhat more flat- 

 tened on their surfaces. Their size in relation to the whole body was still smaller than in the Amphis- 

 bcence that were dissected, for they were scarcely a line in length, and their greatest breadth was only a 

 little more than one third of a line. They were white in colour, and the direction of their greatest 

 diameter was perpendicular. In all three species the bones in question lay at a considerable distance from 

 the vertebral column and from one another. Moreover, they were not connected by means of ligaments, 

 either with the vertebral column, with the ribs, or with each other, but were retained in position by 



Whilst these sheets were passing through the press Professor Huxley put into my hands Dr. Carl 

 Gegenbaur's most important memoir, ' Untersuchungen zur vergleichungen Anatomic der Wirbelthiere/ 

 Zweite Heft, August, 1865. I must refer the reader to the work itself, as my acquaintance with it 

 was made too late for me to analyze its contents. 



1 The terms in brackets and italics are added to make Rathke's description harmonise with my 

 own. W. K. P. 



