TRANSACTIONS OF THE SECTIONS. 87 



shape and sculpture. But I am not disposed to unite the two species. In T. 

 striata the ribs are much narrower than in the typical T. caput-serpentis and are 

 finely beaded or tuberous, especially towards the beaks, and they are not so 

 close together as in the variety septeiitrionalis. This question of identity depends, 

 however, on the capability of hereditary persistence which some species possess ; 

 and although a certain degree of modification may he caused by an alteration of 

 conditions in the course of incalculable ages, our knowledge is not sufficient to 

 enable us to do more than vaguely speculate, and surely not to take for granted 

 the transmutation of species. We have no proof of any thing of the kind. Devo- 

 lution, or succession, appears to be the law of nature ; evolution (in its modern 

 interpretation) may be regarded as the product of human imagination. I am not 

 a believer in the fixity of species, nor in their periodical extinction and replace- 

 ment hy other species. * The notorious imperfection of the geological record ought 

 to warn us against such hasty theorization. We cannot conceive the extent of this 

 imperfection. Not merely are our means of geological information restricted to 

 those outer layers of the earth which are within our sight, but nearly three fourths 

 of its surface are inaccessible to us, so long as they are covered by the sea. Were 

 this not the case, we might have some chance of discovering a few of the missing 

 links which would connect the former with the existing fauna and flora. It is 

 impossible even to guess what strata underlie the bottom of the ocean, or when the_ 

 latter attained its present position relatively to that of the laud. The materials of 

 the sea-bed have been used over and over again in the formation of the earth's 

 crust ; " Omnia mutantur, nihil interit ; " * and the future history of our globe 

 will, to the end of time, repeat the past. What does Shakespeare say, as a geolo- 

 gist, to such cosmical changes ? 



" heaven ! that one might read the hook of fate, 

 To see the revolution of the times 

 Make mountains level, and the continent 

 (Weary of solid firmness) melt itself 

 Into the sea ! and, other times, to see 

 The heachy girdle of the ocean 

 Too wide for Neptune's hips." 



There is also the difficult problem of submarine light, evidenced by the facts 

 of deep-sea animals having conspicuous and well-formed eyes, and of the shells 

 of deep-sea Mollusca being sometimes coloured, which is yet unsolved. 



Much more remains to be done ; and probably many generations, nay, centuries, 

 must elapse before the very interesting subject which I have now ventured to sub- 

 mit to your consideration will be mastered or thoroughly understood in all its varied 

 aspects. Let us then confess our ignorance, and conclude in the sublime words of 

 the Psalmist : — " Thy way is in the sea, and thy path in the great waters, and 

 thy footsteps are not known " f. 



Anatomy and Physiology. 



Address bxj Professor A. Macalistee, M.D., M.R.I.A. 



Dubing the thirty-six years which have elapsed since the former meeting of the 

 British Association at Plymouth, in the year 1841, the whole aspect and position of 

 the system of sciences now grouped under the name of Biology have undergone a e< im- 

 plete change. Then they were little more than crude and disconnected clusters of 

 facts, whereas now they have become sciences so organic in their unity and so phi- 

 losophic in their basis that they have risen wholly above the reproach which the 

 cultivators of the mathematical sciences were once wont to cast upon the biologist. 



* Ovid, Met. xv. 105. t Ps. Ixxvii. 19. 



