238 Drs. T. L. Brunton and J. T. Cash. Action of [Mar. 31, 



"habitat ; otherwise, North America, east of the Rocky Mountains, is 

 the nearest region in which the Ghelydridce are to be fonnd. Bat 

 Chelydridce, and, indeed, species of the genns Ghelydra, occnr in 

 Upper Miocene (CBningen) and in Eocene formations in Europe, 

 Moreover, Platychelys, of the Upper Jurassic series of Bavaria and 

 Switzerland is regarded by Riitimeyer as an early form of the group. 



Lord Howe's Island is about 200 miles from the nearest Australian 

 mainland, and something like 400 miles, as the crow flies, from the 

 Darling Downs, in which the caudal armour, which has been ascribed 

 to Megalania, was found. The discovery of Geratochelys, therefore, 

 has an interesting bearing on the question of the former extension of 

 Australia to the eastward, on the one hand ; and of the possible 

 derivation of such forms as Ceratochelys from Asia, on the other 

 hand. An elevation of the sea bottom of 6000 feet would place 

 Norfolk Island and Lord Howe's Island on a peninsula extending 

 from the region of the present Barrier Reef to New Zealand ; and 

 the Florae and Faunae of those islands are known to have special 

 affinities with those of New Zealand and none with those of Australia^ 



Speculations respecting the origin of the Chelonian carapace, are 

 suggested by the discovery of osseous scutes in the vertebral region 

 of the tail, and their coalescence in Ceratochelys to form a sort of 

 caudal carapace, ridged in a manner resembling that of Ghelydra and 

 Platychelys. But the consideration of these points would take me 

 beyond the limits of the present note, 



VI. "Action of Caffein and Theine npon Voluntary Muscle." 

 By T. Lauder Brunton, M.D., F.R.S., and J. Theodore 

 Cash, M.D. Received March 24, 1887. 



From a number of experiments we have found that caffein and 

 theine both cause rigor in the voluntary muscles of frogs. All these 

 experiments were made on Bana temporaria and none on Bana escu- 

 lenta. The action is, however, very variable, the rigor being some- 

 times exceedingly well marked, and at other times not observable. 

 The alteration does not depend on the dose of the alkaloid. When 

 the gastrocnemii of the same frog were treated with solutions of 

 caffein or theine of different strengths, the stronger solution had the 

 most powerful action ; but when different frogs were used, a large 

 dose sometimes had little action on one frog, while a small dose had a 

 powerful action on another. Theine seems to be rather more powerful 

 than caffein, but the quantitative difference between them is slight. 

 There is, however, a marked qualitative difference between them, 

 inasmuch as theine tends to produce rhythmical contractions in the 

 muscle. Complete curarisation quickens the occurrence of rigor. A 



