1910.] Cmniid FonnniiKi; the Veriebrcv. 431 



In the Insectivora there are two iiiahi branches of the internal carotid as 

 described above (p. 247). The course of these branches in the (Hfferent 

 famihes and orders has been carefully described by Winge and others and 

 is noticed especially by Matthew (1909, p. 350). 



"Carotid foramen" of Marsupials, etc. The internal carotids pierce 

 the basis])henoid on either side in Monotremes and Marsuj)ials (except 

 Acrohatcs, p. 223). lliis condition may l)e foreshadowed in the Cynodontia ^ 

 (Fig. IB). A similar arrangement is reported in the Cetacea l)ut in view of 

 the strongly preponderating evidence for Placental affinities this condition 

 in the Cetacea is very likely secondary. The internal carotid occasionally 

 pierces the basisphenoid in certain other Placentals noted by van Kampen 

 (1905, p. 383: Erinaceus, Ccnietes, Vespertilionidte, Orycteropus, Herpes- 

 tin se.) 



The posterior palatine and ■infraorbital foramina also serve to transmit 

 blood vessels. So also the suboptic foramina (characteristic of Insectivores 

 only ?). There are a number of foramina that have some relation to the 

 transverse sinus and jugular vein which are described above (pp. 224, 248). 



The transverse canal (venous) pierces the basisphenoid in Marsupials 

 and Rodents. 



The Vertebrce. 



The vertebrae have so far yielded relatively few characters of much inter- 

 ordinal genetic importance, among which may be cited the following: 



(1) Retention of distinct cervical ribs in Cynodonts antl iNIonotremes, 

 and on the axis of Parameles (p. 152). 



(2) Retention of "intercentra" below the lumbars of certain Insectivora 

 (p. 265) and below the cervicals of the embryonic Bos. The homologv of 

 these elements Avith the intercentra of reptiles is doubted by Weber (1901, 

 p. 86). 



(3) Frequency of the dorso-lumbar formula of 19-20 (D 13-15, L 7-5) 

 among INIonotremes, Marsupials and primitive Placentals (p. 275). The 

 dorso-lumbar formula of Artiodactyls (typicalli/ D 13, L 0) contrasts with 

 the formuliTe of most Perissodactyls (D 18-20, L 6-3). 



(4) Secondary increase in the number of vertebrae, e. g., in the cervicals 

 of Sloths, in the dorso-lumbar region of many Placentals (<?. g., Perisso- 

 dactyls), in the caudal region of Manis and Microgale. In certain instances 

 (e. g., Galeopithecus) this increase may be due to the shifting of the sacrum. 

 Bateson (1894, pp. 106-123) has shown that where an abnormal increase or 

 decrease in the number of vertebrae occurs the vertebrae that find themselves 



1 That is, if the deep fossa between the alisphenoid and basisphenoid in Cynognathus 

 (Fig. IB) really ended in a foramen. 



