234 Miscellaneous. 



species differ in the character of the teeth, especially in numher and 

 form of the premolars. 



In one species from Aliwal ]J^orth the molar teeth are trans- 

 versely wide, ornamented with three transverse ridges, which 

 terminate in a slight cusp both on the external and internal margins. 

 There are not more than nine molars. The crown of the first pre- 

 molar in one specimen is elongated from front to back, and shows a 

 small coronet of rounded marginal cusps. In a species from Lady 

 Frere the molar teeth are narrower and the premolar teeth more 

 numerous, small, and circular in the broken sections. 



Although these skulls are mammalian in aspect, and in some 

 respects make new transitions towards mammals, in technical 

 characters they retain a sufficient number of reptilian structures to 

 permit no doubt that they are true reptiles. The mammaUan 

 resemblances in the skull being paralleled in the other parts of the 

 skeleton, it may be affirmed that these fossils demonstrate a closer 

 affinity between reptiles and mammals than had previously been 

 evident. — From the Proceedings of the Royal Society. (Communi- 

 cated by the Author.) 



The Transformation of the Aortic ArcJies in the Frog. 



By M. S. JoiTKDAXJf. 



In the course of investigations which for several years I have 

 pursued upon frogs I have had occasion to study, by the aid of 

 injections, the transformations undergone by the large vessels which 

 spring from the bulb of the aorta at the time of transition from 

 aquatic to aerial life. The results of my observations differ to such 

 an extent from those which are recorded in the treatises on zootomy, 

 that I have decided to present them to the Academy. 



"We know that in the tadpole of the frog the gills are four in 

 number. The f 'urth, which is situated behind the rest, is con- 

 siderably less developed than the other three. 



In order to render my description more intelligible I shall have to 

 modifj' the customarv terminology in certain respects. I designate 

 the great vessels, four in number, which carry the venous blood to 

 the gills, bulbar arches (crosses bidbaires) ; hypobranchial vessels is 

 the term that I apply to the portion subdivided from each of these 

 arches which distributes itself to the giUs, and by epibranchial 

 vessels I mean the portion which brings back the aerated blood to 

 the origin of the arteries which spring from these epibranchials. 

 These arteries are, in the case of the first arch, the carotid Unguals ; 

 in that of the second the aorta : in that of the third and fourth the 

 cutaneous respiratory and the pulmonary. 



The epibranchial vessels are united one to another on each side, 

 at a short distance from the point of their emergence from the gill, 

 by anastomotic branches, which have a longitudinal direction and 

 are termed by me connective branches {rameaux connectifs). 



Finally, it is important to note the presence of a short and wide 

 anastomotic plexus, to which I shall apply the term interbranchial, 



