340 MR. W. H. FLOWEE ON THE OSTEOLOGY OF THE SPEKM- WHALE. 



articular facet for the head of the rib, gradually becomes more distract, and ultimately 

 forms the main transverse process, serially continuous with those of the lumbar region. 

 We have thus in the hinder part of the dorsal region of the Sperra-Whale a perfect 

 repetition of the characters of the cervical vertebrae of ordinary Mammals, as far as the 

 transverse processes are concerned, an upper one springing from the arch, a lower one 

 springing from the body, and uniting at tlieir extremities so as to form a complete bony 

 ring. 



In this important character of the spinal column Hyperoodon agrees with Fhyseter ; 

 and this appears to me one of the most sticking points of affinity between these two 

 genera. In the skeleton of the Hyperoodon in the Hunterian Collection in the 

 College of Surgeons, upper transverse processes are regularly developed ti-om the arches 

 of the dorsal vertebrae as far as the seventh, but cease in the eighth. The lower pro- 

 cesses arising from the body begin in the seventh, which has thus two processes, which 

 (in this immature specimen at least) do not meet at the ends ; but the bony ring is 

 completed by the attachment of the proximal end of the rib to both processes, 

 recalling exactly the condition of the cervical vertebrae of the Crocodiles. In several 

 adult Hyperoodons' skeletons, I have seen the upper and lower transverse processes of 

 the seventh dorsal vertebra united so as to form a complete ring. 



It will be very important to ascertain whether Koyia and the Ziphioids agree in this 

 respect with Physeter and Hyperoodon, as certainly might be predicated from their 

 general affinities. With regard to the first-named, the only published description* of 

 the skeleton at Sydney gives no information on this point ; but the unique skeleton of 

 the Micropteron sowerbyense, belonging to the last-named group, now in the Royal 

 Museum at Brussels, shows the following characters : — The seventh dorsal vertebra has 

 a transverse process springing from the arch ; to this the tubercle of tlie seventh rib is 

 articulated, while its head joins the body in the usual way. The eighth vertebra has 

 no process from the arch, but one projecting from the body at a level with the facet 

 for the attachment of the head of the seventh rib ; to this the end of the eighth rib is 

 fixed. The transposition of the transverse process from the arch to the body is thus 

 as abrupt as in Physeter and Hyperoodon, the only ditferencc being that the two pro- 

 cesses do not coexist on any one vertebra as in those genera. The principle, however, 

 is the samef. 



Lumbar Vertebrae. — The eight lumbar vertebrae present a remai'kable similarity to 

 one another, both in form and dimensions. Their bodies increase slightly but pro- 

 gressively in length from the first to the last. One of their most characteristic features 

 is the form of their infero-lateral surfaces, much hollowed out and converging to a strong 



» Wall, op. cit. 



t For the condition of the rib-attachments in Plaianista and Inia, in some respects intermediate between 

 those of the Physeteridm and Delphinida, see '• Description of the Skeleton of Inia geoffrensis," &e.. Trans. 

 Zool. Soc. vol. vi. pp. 98-103. 



