138 PROFESSOR STRUTHERS. 



unfinished condition, the subcartilaginous border, f inch thick 

 at the middle, becoming narrower on the sides to within an 

 inch of the base, where the edge becomes thin and completed. 

 There is no indication of bifurcation at the front.^ It is bent 

 downwards very much at its base, this being the sole cause of 

 the antero-posterior concavity of the inferior surface of the bone. 

 On the upper surface the cervical process is rather suddenly 

 bent downwards at the middle, rendering it convex, to which 

 the forward thinning of the process also contributes. The 

 moderate longitudinal convexity on the posterior half of the 

 upper surface of the sternum is owing to the greater thickness 

 of the beam between the wings, not to any bending down of 

 the posterior process. It may be noted that the concavity on 

 the border between the cervical process and the wing is not 

 quite so deep on the left side as on the right. 



39. Relation of the Sternum to the First Rib. — The 

 macerated bones alone would be very apt to mislead in the articu- 

 lation of the skeleton. As Eschricht has shown with his usual 



1 The variation in this respect in the fin-whales is great. In my 35-feet-long 

 B. horealis, the cervical process, after a length of 1^ inch, has bifurcated for half 

 an inch, ossifying into a large undivided plate of cartilage, 2 inches in length by 4 

 in breadth. In the 50-feet-long B. musculus the cervical process, Sg inches long, 

 shows no appearance of past or coming bifurcation. In the figure given of B. 

 musculus by Professor Flower {loc. cit.) the wings and cervical process form one 

 great irregular semilunar plate with no sign of bifurcation, present or obliterated. 

 In a sternum in my possession, found on the shore, which appears from its other 

 characters to be that of B. musculus, the anterior process is very like that in the 

 figure given by Professor Flower, except that there is a great median fissure, about 

 5 inches deep by 1 inch wide, nearly closed in front. In my figure of the 64-feet- 

 long B. musculus {loc. cit., 1871), the small foramen is so far back that it might 

 be attributed to the position of a blood-vessel rather than to a former bifur- 

 cation of the bone. In two figures of the sternum of B. musculus given by 

 Van Beneden and Gervais (Joe. cit., \A. xii.-xiii. figs. 14), one of them from a 

 young animal, it is bifurcated anteriorly. The same authors give diagram figures 

 of the sternum of Megwptera [loc. cit., p. 128), showing a deep bifurcation closed 

 in to form a foramen, and then the foramen obliterated. In their figure of Megap- 

 tera Lalandii (pi, ix. lig. 5) the bone is widely bifurcated for more than half of 

 its entire length, and they speak of the sternum of Jlegaptera longimana and 

 Megaptera Lalandii as "assez semblable " (p. 134). The sternum of this Megap- 

 tera would, to all appearance, never have bifurcated, nor is there any sign of a 

 fiUed-up aperture. The smooth inferior surface shows the blood-vessel grooves 

 and perforations radiating from the middle thick part on the posterior half of the 

 bone (the perforations towards the thick part), outwards on the wings, and for- 

 wards, symmetricnlly and undisturbed, on the cervical process. 



