TRANSACTIONS OP THE SECTIONS. Ill 



species of Fusus, which had been obtained from the museum of Mr. 

 Fryer. 



On the Formation of Angular Lines on the Shells of certain Mollusca. 

 By J. E. Gray, F.R.S., ^c. 



The annular marks, and those in the direction of the growth of the 

 shell, and in the substance of the shell itself, are easily explained by 

 the increased or diminished degree of activity of the secreting surface 

 of the mantle. But the coloured angular lines are not so easily ex- 

 plained. Mr. Gray supposed that the colouring of the shell was the 

 consequence of glandular secretion ; that, as the shell increased in size, 

 there was a tendency to divergence in the glands. He stated, that it 

 frequently happened in the progress of growth, that these glands were 

 obliterated, and the immediate consequence of this obliteration was the 

 production of a new gland : this gland was double, and, as it had a 

 tendency to diverge, it formed two angular lines which proceeded to a 

 certain distance, when it met with a gland formed in a similar way to 

 itself, and, on meeting, it became obliterated : after this obliteration, a 

 new double gland was formed, which proceeded in the same mode as 

 the first, and thus produced the angular coloured lines apparent on so 

 many shells. 



Notice of the Womhat. By 3. E. Gray, F.F.S., Sfc. 



Mr. Gray stated, that in the Museum of the Natural History Society, 

 was the wombat which was sent by Bass to Bewick, and from which 

 he took his original description : from a misprint, this specimen was 

 said to have more teeth than it really has ; and, on this account, Illiger 

 having seen a specimen of the wombat, supposed this must be another 

 genus, and named this one in his work, Amblotis wombattus. The con- 

 dition, too, of this specimen assisted in the mistake, for, having been 

 originally kept in spirit, it had lost its true colour. 



On the Boring of Pholades. By J. E. Gray, F.R.8., ^c. 



A difference of opinion prevails as to Avhether the action of these 

 animals in excavating the rocks in which they are found is chemical 

 or mechanical. At one time Mr. Gray was inclined to think it was 

 the former ; however, he had lately an opportunity of remarking the 

 action of these animals in the chalk at Brighton, and he now believed 

 it to be mechanical. He then exhibited several specimens of chalk 

 which had been bored by the pholas, and pointed out some circular 

 grooves which were made in their interior by spines on the outside of 

 the shell, as well as a central impression produced by an elongation of 

 the shell to a point at its inferior surface. He stated that the animal 

 did not occupy the whole of the cavity it made, but the upper part 

 only. Why he had formerly supposed the action of these animals on 



