raOCEEDINGS OF SOCIETIES. 19 



were so abundant in former ages, and of which we find very few species at 

 present in existence. The Hypodonts, with compressed and obtuse teeth, 

 are found in the newer secondary strata, and have now completely dis- 

 appeared, leaving no representative. On the (iontrary, the true Sharks, with 

 ■ sharp teeth, were veiy rare in the older formations, and increase in numbers 

 as we ascend to the present epoch." 



The Doctor then observed, that the statement of Agassiz, that all the 

 fishes of the older strata were heterocercal, that is, that the caudal vertebraa 

 were prolonged to the extremity of the tail, did not appear to be entitled to 

 the importance which has been assigned to it. As a general statement, it was 

 valuable as a guide to the practical ichthyologist ; and had the same import- 

 ance as the fact that no deciduous horned ruminant is found in Africa, or that 

 prehensile tailed monkeys are found only in America. As a philosophical 

 generalisation it was very unimportant. Thus the cartilaginous fishes of the 

 present day are as heterocercal as those of the coal formation ; and in the 

 modern Batrachians, the deciduous tail of the Frog, and the persistent one 

 of the Salamander, did not, in like manner, appear of much consequence. 

 Even in the higher Mammifers, it is found that some of the bats have per- 

 sistent tails, while in others that organ had disappeared. 



After some conversation among the membei'S, and a vote of thanks passed 

 to Dr. Scouler, for his highly instructive Lecture, of which the above is a 

 mere outline, the meeting adjourned to the first Tuesday in September. 



Sept. Mh. The ordinaiy Monthly Meeting of the Society was held this 

 evening, Mr. Fbasee, President, in the Chair. 



The Minutes of last meeting having been approved of, Mr. Godrlie stated 

 to the meeting the fact of a rare sea-weed, Cystoseira ericoides, having been 

 collected by him at Ayr-heads. Though, hitherto, rare in Scotland, this 

 plant he found not unfrequently, during the months of July and August 

 last, on this part of the west coast, apparently drifted away from its neigh- 

 boui'ing habitats. 



Mr. Duncan exliibited specimens of Cuscuta epithymum, collected by himself 

 at Barrhill, near Kirkintilloch, hitherto apparently unnoticed in Scotland. 

 It was found, as usual, parasitical on the flax, on which plant, Di*. Scouler 

 remarked, it was found in great plenty in Germany. Mr. Duncan also men- 

 tioned his having collected Sagittaria sagittifolia in plenty, on the coast near 

 Inchinnan Bridge. 



The Secretary then exhibited several species of the genus Pontia, Fab., 

 illustrative of the geographical distribution of these butterflies, and of the 

 generic similarity in the species of various latitudes. 



Dr. Scouler then gave a Lecture on the vertebral development of the 

 cranium. He stated, that about the commencement of the present century, 

 the idea, that the cranium is comjDosed of a series of vertebraj, occurred ta 



