ANATOMY OF MEGAPTERA LONGIMANA. 123 



part of the axis, is 1 inch broad on the following more anterior 

 vertebrae, and becomes less marked on the more posterior. The 

 body is concave transversely on each side of it, so that, but for 

 the ridge, the whole upper surface of all the bodies would be 

 transversely concave. In Megaptera the median ridge is less 

 marked. It begins at the same place on the axis, is narrow on 

 the 3rd, mesially grooved on the 4th, less marked on the 5th, 

 and very Mnt on the 7th. Transverse concavity on the upper 

 margins of the bodies ceases on the 5th, and on the 7th the 

 whole upper surface of the body is convex transversely (con- 

 tinued on the dorsal), presenting a marked contrast to the 7th 

 of this B. musculus. 



Spinous Processes of the Five Posterior Cervical Vertebra'. — 

 The 3rd and 6th have been injured. The 4th (| inch in length) 

 and the 5th (f inch) are a little longer, the 7th (1^ inch) a little 

 shorter than in B. musculus. The 7th has a backward direc- 

 tion in Megaptera, like the anterior dorsal spines ; in B. mus- 

 culus it is nearly straight up, like that of the 1st dorsal, After 

 the 4th, the spines in Megaptera have a more unfinished 

 appearance than those of the B. musculus. 



Lamincc. — The laminae are necessarily longer (transversely) 

 in Megaptera, from the farther-out position of the articular 

 processes, but the chief differential characters are their breadth 

 (antero-posteriorly), filling up the spaces, and their much greater 

 thickness and convexity on the upper surface, in Megaptera. 

 The convexity appears as a rough bulge occupying about the 

 middle half of the lamina transversely, and the posterior | of 

 the breadth. The same is seen on the 1st dorsal and less on 

 the 2nd. These prominences seem to correspond to the ana- 

 pophysial processes previously described in B. musculus (loc cit, 

 p. 24, and fig. 3, 1872), but they are not prolonged behind the 

 lamina. They are rough on the surface and evidently for the 

 attachment of muscular or ligamentous structures. 



The laminae of the 3rd and 6th vertebrae have been injured 

 from the rough usage they received in Dundee harbour, but, as 

 far as can be judged now, the spaces have been filled up by the 

 anterior overlapping the posterior, except on either side of the 

 3rd arch, although it cannot be determined how far this is from 

 breakage of the thin anterior edge of the 3rd and 4th lamina. 



