118 



ESCHRICHT AND REINHARDT 



of the whalebone-whales. We know that in all whalelione-whales only the first pair of ribs is con- 

 nected with the sternum. All statements disagreeing with this we do not hesitate to call erro- 

 neous. That the Greenland whale is no exception from this rule, will be evident to our readers 

 when they look at Plate II, fig. 3, which, as we have stated abeady, is drawn from a photograph 

 of this reo-ion in our twenty-two feet long skeleton, in which all the parts were still preserved in 

 their natural connection. 



It beino- only the first pair of ribs which is connected with the sternum, we should not be 

 surprised if in all whalebone-whales this pair were the only one provided with sternal ribs, 

 whether ossified, as in the toothed-whales, or cartilaginous, as in land-mammalia generally. 

 But that these bones foimd in all air-breathing vertebrated animals should be entirely wanting 

 even in this foremost pair of ribs of the whalebone-whales, must justly be considered as a 

 strano-e anomaly. Now we have at length been convinced, in examining the foetus preserved 

 in spirit, that these sternal ribs are not indeed wanting in it. 



As lono' as the anterior rib of either side was still enclosed in its extraordinarily (one line) 

 thick periosteum, it seemed indeed to be immediately connected with the sternum, also enclosed 

 in its perichondrium of no less considerable thickness ; and as far as everything enclosed in the 

 same periosteal membrane be considered as one single bone, each of these ribs must also be con- 

 sidered as one such ; but, as far as we know, the vertebral and sternal parts of each rib are also 

 enclosed in one common thick perichondrial or periosteal membrane in the foetuses of the other 

 mammaha. The question, therefore, whether the sternal ribs were wanting, had not as yet 

 been answered in this way. It was therefore necessary to cut through this thick exterior mem- 

 brane in order to get a sight of the bone itself, and the adjoining figure gives a representation 

 (half the natural size) of what we discovered. 



A is the sternum still entirely cartilaginous ; 

 its perichondrium is removed on all sides, so that its 

 external surface is completely bare, and the perichon- 

 drial membrane is only indicated by means of a 

 double line. In the same way the periosteum has 

 been removed, and indicated in the figure round the 

 fragment of that part of the anterior rib at the right 

 hand side, which is placed nearest to the sternum. 

 It will now be seen that this portion of the rib con- 

 sists of several parts somewhat dissimilar to one 

 another, and what, we think, will be perfectly decisive 

 in answering om- present question, the interior of 

 the periosteal sheath, rather loosely connected with 

 the surface of the bone, is divided by means of a 

 very fine but strong membrane into two separate 

 parts, the one exceeding the other very much in size, 

 in which is found the rib properly so called, or the 

 vertebral rib {5 and c), and the other, very small in 

 comparison, in which the sternal rib (ci and e) is 

 enclosed. Each of these osseous parts had its own special character. Though almost like 

 a sponge impregnated with spirits of wine, yet the long vertebral rib was, to about four 



