ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 299 



perfect roof ; the cerebellum resembles that of ArgyropeUeus, and is 

 primitive in the slight development of the valvula cerebelli ; the medulla 

 is essentially like that of other fishes. The cranial nerves are described 

 at length. 



Pairing of Rana temporaria.* — W. Wolterstorff records some 

 interesting facts concerning R. temporaria, observed by Dr. Dieck on an 

 expedition in Asturias. In a pass (1400 m. high) between Leon and 

 Oviedo, he observed thousands of gigantic well-nourished reddish-brown 

 frogs in copula upon the snow. They were progressing towards a brook 

 which was just thawing. It appears that they pass the winter under the 

 snow ; under the sexual impulse they scrape out channels through which 

 they reach the surface and make for the water. 



Types of Limb-Structure in Triassic Ichthyosauria.t — J. C. 

 Merriam discusses the four types of limbs known in the Triassic 

 Ichthyosaurs. They show an unexpected degree of differentiation when 

 compared with the limbs of Jurassic genera. But in spite of the 

 differentiation shown in the Triassic types, they have all retained certain 

 primitive characters not common in the later forms. All show a 

 separation of radius and ulna, and in all excepting Shastasaurus osmonti 

 these elements are elongated and the radius is constricted or shafted. 

 The presence of these and other primitive characters in so many other- 

 wise different forms furnishes us with much stronger evidence of the 

 origin of the Ichthyosauria from generalised shore forms than could 

 have been given by the single type known to Baur, who nevertheless 

 reached the conclusion that the limbs of the Triassic Ichthyosaurs come 

 nearer to the type found in the primitive Reptilia than do those of the 

 later representatives of the order, and argued that the group bore the 

 same relation to the Rhynchocephalia that the cetaceans bear to the 

 primitive mammals. 



Ear-Bones of Vipera and Tropidonotus.J — W. Moller has inves- 

 tigated the development and innervation of the ear-bones in these two 

 forms by means of reconstructions from serial sections of embryos. 

 The columella arises from the caudal end of the capsule which de- 

 velops around the membranous labyrinth. From this it grows as a 

 conical projection towards the hyoid arch, to end near the outer open- 

 ing of the first gill-cleft. In the beginning there is no clear dis- 

 tinction between the origin of the columella and the rest of the 

 labyrinth capsule. At all the stages examined the columella was of 

 uniform structure throughout, and nothing to indicate its formation in 

 two parts was found. The tuberosity at the hinder end of the quadrate 

 observed by Hassa is probably a stylo-hyal which has fused with it. 

 This stylo-hyal, the author finds, is united by a joint with the columella. 

 Peculiar granule-bearing cells were observed around the columella at 

 the stage of formation of the primitive cartilage. Numerous details 

 regarding innervation are given in the paper. 



* Zool. Anzeic, xxviii. (1905) pp.53C-S. 



t Amer. Journ. Sci., xix. (1905) pp. 23-30 (7 figs.). 



J Arch. Mikr. Anat., lxv. (1905) pp. 439-97 (2 pis.). 



