278 PROCEEDINGS OF THE 



the Fern islands or pass by them at certain seasons of the year. 

 I have only enumerated those birds about which I found in my 

 notes matter that seemed to me worth recording in the Society's 

 Proceedings. 



III. — On Injured S])ecimens of Elssoa striata. By Mr 

 David Eobertson, F.L.S., F.G.S. 



These injured specimens of Rissoa striata that I bring before 

 you were met with in post-tertiary clay taken from an excava- 

 tion for Paisley Gas Tank. The larger one has been injured 

 about the time of the growth of the fifth whorl, and the body 

 whorl that succeeds takes a bend and swells to an abnormal 

 extent. The most interesting point is that this abnormal whorl 

 is devoid of striation. The process of striation seems to have 

 ceased at the time of the injury, from which we are led to 

 believe that when the animal is in possession of all its faculties 

 it is furnished with a special appliance for the formation of these 

 striae, and when that appliance is destroyed, the striae con- 

 sequently cease to be formed. Nevertheless, the growth of the 

 shell goes on; but in the case before us it has, from the point 

 of injury, grown out of proportion to the first formed whorls. 

 Now, the question arises, whether the loss of this faculty of 

 striating is the cause of the increase of growth of the shell 1 



Another shell of the same species from the same locality 

 tends to strengthen this view. It has sustained a similar injury, 

 but to all appearance of less extent, and at an earlier stage of 

 growth. It is also curved at the point of injury in the same 

 manner as the other, and from that point the striations are 

 greatly weakened, although not altogether wanting, and the 

 whorls succeeding the injury have also grown out of proportion. 

 This animal, not having sustained so much injury as the first 

 example, has been still able to continue the striations, although 

 in a weak degree, and you will observe that the striae almost 

 disappear as they approach the outer lip, which we may con- 

 sider as proving that after the injury the power of striating has 

 rather been declining than recovering. 



The great difficulty in this case is the want of a sufiicient 

 number of examples to prove satisfactorily that the destruction 

 of the one organ affects the function of the other. In a palaeon- 

 tological point of view it should be remembered that such cases 



