REPTILIA: VARANOSAURUS 97 



altogether too small for the attachment of a ehevron. That 

 between the second and third is larger. At the end of the third 

 there is a large facet for the attachment of a chevron, whose union 

 was almost wholly with the third. Lying near these were several 

 large chevrons with an obtuse extremity, and a shorter one with 

 a more pointed extremity. I have figured this short one as attached 

 to the end of the second centrum, with the three large ones following 

 it; on further reflection I very much doubt whether there was a 

 chevron attached here — in other words, there were doubtless two 

 pygal vertebrae as in Casea and other forms; otherwise the chevrons 

 would have projected into the pelvic cavity, as they have been so 

 often figured in Diplodocus. 



The spines of the anterior caudal vertebrae are nearly vertical; 

 at the sixth the spine is shorter, more pointed, and inclined a little 

 forward. With the twelfth — that is, the vertebra bearing the last 

 transverse process or co-ossified rib — the spines have become mere 

 tubercles, and thence onward they do not change much, becoming 

 entirely lost before the end of the tail. 



The ribs of the first four caudal vertebrae are attached by a 

 short, stout proximal end to both arch and centrum. On the 

 underside near the body a pit or cavity seems to indicate the natural 

 division into head and tubercle, the capitular portion descending 

 lower on the front margin of the centrum. These four ribs decrease 

 in size ; they are all pointed, with the point curved directly backward 

 parallel with the axis of the tail, and they are horizontal. The 

 much smaller fifth rib is directed outward horizontally and is also 

 pointed at its extremity. The following ribs or processes decrease 

 in length, terminating as a small tubercle on the twelfth; they 

 ascend on the centrum as far back as the eighth. Thence to 

 the last one preserved in the connected series, the forty-seventh, 

 the centra are similar, becoming gradually more slender, the 

 spines finally becoming obsolete; their chevrons are slender to 

 the extremity. 



Pectoral girdle and extremity (Plates IV-VIII). — ^The ossified 

 pectoral girdle is composed of the scapula and so-called procora- 

 coid, clavicles, and interclavicle. The posterior coracoid, the 

 so-called true coracoid, is unossified in all the numerous specimens 



