T y6 [ pr °c B.N.F.C, 



Dr. Charlesworth, in the course of his lecture, said the imper- 

 fection of the geological record was shown by the conditions under 

 which organisms are preserved — illustrated in case of Archse- 

 opteryx — only one feather and two specimens found, and that in a 

 quarry that has been worked since time immemorial. One of the 

 earliest laws to be established was that of Cuvier, "Law of 

 Correlation," that it was possible to predict from a part the 

 structure of other parts. Attempts to apply this law had failed in 

 practice. One of the laws established by Palaeontology is that of 

 analogous or convergent evolution. A case cited in support was 

 Shark, Ichthyosaur, and Dolphin — i.e., Fish, Reptile, Mammal — 

 all of which approximate to the same form, though possessing 

 entirely different internal structures. Closely allied to this law is 

 that of heterogeneous homomorphy illustrated by Terebratula 

 diphya. The lecturer then worked up through successive geological 

 formations, showing by slides how the predominant form in any 

 formation was succeeded by a higher type in zoological scale — 

 Fish, Amphibia, Reptiles (Sauropterygia, Tethyopterygia, and 

 Dinosauria), and finally Mammals. The origin of the great groups 

 is unfortunately wrapped in mystery. The lecturer gave support 

 to the theory of discontinuous mutations or " jumps " in evolution 

 illustrated in the case of fishes. What was called the law of 

 recapitulation was shown in case of Ammonites, and the antlers of 

 the Cervidse. The history of Whales was described from early 

 Eocene Prozeuglodon to the present Whale, and the gradual loss 

 of hind limbs until only part of the latter was now present, buried 

 in the flesh of modern Whales. Dr. Charlesworth then touched 

 upon the irreversibility of evolution, and showed how if a digit or 

 a tooth be lost it is lost for ever. Also how a specialised organ 

 can never again become generalised. Although most forms have 

 changed, yet some have remained practically unaltered throughout 

 geological time — e.g., the Medusa of to-day — but little different 

 from Medusites lindstroemi of pre-Cambrian seas. The lecturer 

 then went on to show the signs of groups when in their declining 



