436 SUMMARY OF CURRENT RESEARCHES RELATING TO 



convinced that skeletoblasts migrating from the epidermis are the 

 formative elements. 



Development of Pectineal Process.* — N. G. Lebedinsky has studied 

 this in young Ratitse. The anterior margin of the acetabulum of birds 

 is formed from the processus ilii acetabularis pubicus. A blunt process, 

 the eminentia iliopubica, is formed where the processus ilii acetabularis 

 pubicus and the pubis unite. On the processus ilii acetabularis ilii there 

 is often a pectineal process, or spina iliaca, on which the ambiens muscle 

 is inserted. Mehnert showed that the eminentia iliopubica can be seen 

 in the half-grown bird whether there is a pectineal process or not. 

 Parker and Baur have shown that the pectineal process of the kiwi is 

 formed by both ilium and pubis ; Burge, Mehnert, and Lebedinsky 

 have shown that the pectineal process of Carinatae is formed from the 

 ilium only ; Lebedinsky now shows that the pectineal process of the 

 ostrich (Struthio) is formed from the pubis only. Therefore the pecti- 

 neal process cannot have any phylogenetic importance. It is probably 

 a new acquisition within the class of Birds. 



Development of Lacertilian Sternum and Pectoral Girdle.| — S. 



Bogoljubsky has studied Lacerta, Anguis, and Ascalabotes embryos. 

 As regards Lacerta, the primordium of the sternum appears without 

 assistance from ribs, from two paired triangular mesenchymatous 

 streaks which lie on the sides of the embryo opposite the distal ends 

 of the first two ribs. The primordium appears after that of the shoulder- 

 girdle. The girdle-primordium appears after that of the basis of the 

 limb. It includes at first a scapular region, a coracoid region, and a 

 part of the clavicular region. The cranial part of the girdle, becoming 

 joined to the epidermis, separates off from the rest of the connective- 

 tissue primordium, except a connexion at its proximal (dorsal) end. 

 Separating away from the skin, it ossifies directly into the clavicle. 

 The coracoid region differentiates into prasscapula, procoracoid, and 

 epicoracoid. The interclavicles are outgrowths in a caudal direction 

 from the median primordia of the clavicle. In Anguis the sternal streaks 

 are not helped by ribs. In Ascalabotes the ribs coalesce early with the 

 sternal streaks ; in fact, an interval between them was not demonstrated. 



Embryonic Circulation in Axolotl.J — F. Houssay returns to a 

 difficult question which he discussed in 1893. A cardino- aortic pri- 

 mordium gives origin to the aorta and a common cardinal vein. The 

 latter gives rise to a procardinal vein and a cardinal vein. The cardinal 

 vein gives origin to the inferior vena cava by another splitting. The 

 pronephros is connected with the procardinal vein and the cardinal vein ; 

 the mesonephros with the cardinal vein and the inferior vena cava ; the 

 metanephros with the inferior vena cava. 



* Anat. Anzeig., xlvi. (1914) pp. 84-9 (2 figs.). 



t Zeitschr. wiss. Zool., ex. (1914) pp. 620-66 (7 pis.). 



X Arch. Zool. Exper., liv. (1914) Notes et Revue, No. 5, pp. 101-8 (2 figs.). 



