24 



W. LlLLJEBORG, 



well as on the preceeding, (9 th , 10 th , or 11 th ) and 5 th , 6 th and 7 th there 

 is above the posterior edge of the base of the lateral processes a hollow 

 (fossa) sharply defined in front, which is deeper in the 5 th , 6 th and 7 th . 

 At the ends the lateral processes are thickened, but are yet provided with 

 but an inconsiderable articulating hollow, which extends from the middle 

 of the extremity obliquely under its posterior angle. Dimensions of this 

 vertebra: Breadth of corpus 9-f-' ; height of d:o 7"; length of d:o 7|"; 

 height of the vertebra to the top of processus spinosus 19f ; rectilinear distance 

 between posterior angles at the ends of lateral processes 2' 8-f"; length of la- 

 teral processes in anterior border 13"; breadth of their ends 5f-"; length 

 of processus spinosus in anterior border about 9"; distance between external 

 edges of processus mammillarcs 6y". 



The vertebra, which we take to be the 1 st lumbosacral vertebra (PI. 

 III. figg. 18, 19 and 20) is distinguished from the dorsal vertebrae in ha- 

 ving its lateral processes longer, thinner, and less inclined backward, and 

 without articulating surface for the ribs , and from the other lumbosacral 

 vertebrae by these processes being thicker at the ends than in them. As 

 for the rest in form it differs but little from the hindermost dorsal vertebrae, 

 but has the corpus a trifle higher, the foramen spinale of greater height 

 than breadth, and the distance between the external edges of the processus 

 mammillares less *). It is by this characterized as a lumbar vertebra. Viewed 

 endways the corpus is rounded oval, with the transversal dimension largest, 

 and the upper border of the anterior end very slightly concave, but the 

 same edge on the posterior end straight. The corpus on the lower side 

 along the middle is very convex but presents no ridge. The lateral pro- 

 cesses are very thin, especially at the anterior border, but at the point 

 forwards they are thicker, especially the left. The processus spinosus dis- 

 plays about the same form as in the last described dorsal vertebra , but has 

 not so broad a point when viewed from the side. The right processus 

 mammillaris stretches farther forward than the left. Dimensions of this ver- 

 tebra: Breadth of corpus 9]"; height of d:o 7|"; length of d:o 8", di- 

 stance between extremities of lateral processes 2' 10y"; length of lateral 

 processes 13"; height of the vertebra to the end of processus spinosus 20j-"; 

 length of processus spinosus about 13"; distance between external borders 

 of processus mammillares 5f-". 



The 2 nd lumbosacral vertebra is similar to the first, but the lateral 



l ) In the form of the end of the lateral processes it agrees very nearly with 

 the 1 st lumbosacral vertebra of the Balaena rnysticetus. 



