ANATOMY OF MEGAPTERA LONGIMANA. 73 



expanding at both ends. On the next four again it is a sharp 

 ridge, broadening out on the posterior J or J- into a triangular 

 surface, more marked as we go back, but on the 10th it shows 

 no tendency to the bifurcation presented by the 1st caudal for 

 its chevron bone. 



The subvertebral ridge shows itself on the dorsal region 

 from the 5th to the 12th. The first five dorsal bodies are, on 

 side view, rather convex below, the 4th decidedly so, but, 

 unlike the cervical, have no distinct median ridge. Behind the 

 5th they are a little concave below, notwithstanding the crest, 

 except the 7th and 9th, which are nearly level below. Seen 

 from below, this ridge on the dorsal vertebrae is broad on the 

 more anterior, narrow on the more posterior, of these vertebrae. 



[In B. musculus the subvertebral ridge is present, but low and blunt 

 on the five anterior dorsal ; reappears better marked on and after the 

 13th dorsal; is more decided on the 2nd lumbar, and, after the 2nd, 

 throughout the lumbar region is projecting enough to fill up the 

 concavity of the bodies. Seen from below, the ridges are not flattened 

 out except at their extreme ends.] 



7. COSTAL MARKS. The bodies of the 7th cervical and 1st 

 and 2nd dorsal vertebrae present tubercles on their hinder part. 

 That on the 7th cervical is serial with the inferior transverse 

 processes, those on the 1st and 2nd dorsal are respectively 1 inch 

 and 1J to 2 inches higher up. They are elongated vertically, 

 their upper ends at about the middle of the body. The posterior 

 slope presents an unfinished surface, as if formerly cartilage- 

 covered, is convex both ways ; in size, about 2 to 2 J inches 

 vertically, f to 1 inch in breadth ; that on the 1st is the broader, 

 that on the 2nd the longer vertically ; that on the 7th cervical 

 is a little smaller than the one on the 1st dorsal. The 3rd 

 dorsal, on the corresponding part of the body, has a narrow 

 crescentic mark about J inch broad, as if costal ; best marked on 

 the left side. Each of these costal marks is about on a plane 

 with the end of the transverse process of the vertebra behind. 

 As the ribs fall short of reaching the bodies, these marks can 

 have attached only the ligament prolonged from the rib to the 

 body of the vertebra in front. 



[In B. musculus, costal tubercles exist on the 7th cervical and 1st, 

 2nd, and 3rd dorsal bodies. They are less elevated, and their surfaces 



