COllllESPONDENC V. 



211 



examination has induced mc to believe that they were not in the un- 

 disturbed brick-earth, but in the lower part of the bed whieh lies immedi- 

 ately upon it, consisting of washed brick-earth, the run of the hill. In this 

 bed, which at this particular point is between 7 and 8 feet in thickness and 

 deepens towards the N.E., there is a great difference between its upper 

 and lower portions, for about 4 feet from the upper surface it contains a 

 very large quantity of flints, below that they are less frequent, and disap- 

 pear as you approach the true brick-earth. At first sight, there seems to 

 be but little or no difference between the lower part of the rain-wash bed 

 and the true brick-earth. Also, from the men that removed the soil im- 

 mediately over the skeletons, I found that there was distinct evidence that 

 it had been disturbed, for part of the upper portion of the bed was found 

 mingled with the lower ; that and the fact that the stone was between the 

 skeletons, close to the skulls, would tend to show that they had been buried 

 there, though perhaps at some remote period. 



I remain, yours sincerely, 



H. F. PtlVERS. 



Sidney Villa, Luton, Chatham, May 25, 18G3. 



Holoptychius and Glypiolepis. 



Dear Sir, — Will you allow me space for a few remarks on communi- 

 cations which have recently appeared in your pages, and which have been 

 suggested at least by articles of mine ? 



And first, as to the restoration of Pteraspis, I intended that in my second 

 diagram the posterior portion of the test should be marked off by a dotted 

 or broken line. I was uncertain as to the exact position of the spine, and 

 did not therefore venture to restore that portion, although specimens of it 

 separated from the test were in my possession. Mr. Powric's beautiful 

 specimen clearly indicates the character and position of the spine. But 

 on looking at his figure, it will be seen that it confirms the remark which 

 I made, and which I considered the chief point brought forward by me, 

 even that our Scottish specimens do not show any separation between the 

 cornua and the test, but that the terminal edge on either side of the spine 

 is continuous. I willingly admit that a shade of doubt rests on my first 

 diagram ; but I had virtually stated the ground of that myself, and I con- 

 sider that diagram as of value chiefly in exhibiting the long-snouted form 

 which the shield of Pteraspis sometimes assumes, perhaps indicating spe- 

 cific difference. I put forward my third diagram as entirely conjectural, 

 and, along with my friend Mr. Powrie, must turn to the rocks, in the hope 

 of finding some of those long-entonibcd relics w hich will throw light on 

 the ilia tier. 



And then, as to the case which has been so much debated in your co- 

 lumns, — Holoptychius r. Glyptolepis, — I knew from Mr. Powrie's ow n 

 article in the Quarterly Journal of the Geological Society that Glyptolepis 

 had been noticed in the sandstone of Dura Den, and I simply wished to 

 describe a slab in our local museum from that locality. I did not know 

 what correspondence there might be privately between those who were 

 interested in the matter. I am glad, however, that the attention of Mr. 

 Davies has been called to it, and that he has communicated to your readers 

 the results of his keen discrimination. On the specimen of Holoptychius 

 A/idrrsoni, to which 1 have access, there are several scales towards the 

 posterior part of the body, which display what Air. Powrie calls so pic- 

 turesquely " the crescent of points ;" hut from whai was said in the ' De« 



