1867.1 SALTER AND HICKS LIN-GULELLA. 339 



had very decided bony crutches as a modification of its pectoral fins ; 

 and therefore I think we need not reject such a supposition too 

 hastily in the case of Pteraspis. We have not yet been able to refer 

 all the bony defences (Onchus, as they are called) which abound in 

 the Ludlow bone-bed, the Downton Sandstone, and the fish-beds of 

 the Old Eed, to Placoid fish ; and we may yet be led by these few 

 tracks on sandstone to look out for such adjuncts to the fore limbs 

 of Cephalaspidae. 



At least, all I can say is, that if Pteraspis had not such a bony 

 crutch, I do not see how he could make such an impression on the 

 sand ; and if my impression is not a correct one, I cannot off'er a 

 better, nor suggest what aquatic or amphibious creature could pos- 

 sibly produce successive impressions of the form aud direction I have 

 shown to occur in these, unless it were Pteraspis, or the Acanthodian 

 or Squaloid fishes before mentioned. 



And now comes a very interesting point in proof that these im- 

 prints were made by fishes. If the water were not quite deep 

 enough to float the animal (and that it was not, in the case of track 

 A A*, is certain), then the stroke made by the leaning side must ne- 

 cessarily be shorter and somewhat deeper, and the fin itself behind 

 the defence would touch the ground. In proof that these imprints 

 (fig. 1) are the records of a struggle to attain the water, I need 

 only refer to the specimens (which are placed in the Society's 

 museum), where, on the back of slab 1, the weight of the instru- 

 ments has been such as to indent the sand for more than half an 

 inch, and to penetrate into a layer below, which is, of course, not 

 seen in this specimen. 



I owe the recognition of this circumstance to Prof. R. Owen, 

 whose acumen in determining track-markings is almost an instinct ; 

 and to whom I showed the slab, telling him that I had come to the 

 conclusion it was made by a fish (Pterasjpis), and could be made by 

 nothing else. His reply was very characteristic ; for, turning up the 

 back of the slab, which I had neglected to do, he at once pointed 

 out the depth of the two impressions, which must have been made 

 when the creature was struggling on the shore ; and though he did 

 not hastily adopt my conclusion, he at least convinced me that, if the 

 track was made by a fish, it was a fish out of water. 



4. On a NEW LiNGiJLELLA from the eed Lowee Cambeian eocks of 

 St. Davids. By J. W. Saltee, Esq., A.L.S., F.G.S., and H. 

 Hicks, Esq. 



Fossils in the red Cambrian rocks are so rare, that no apology seems 

 due for introducing a single small specimen, lately gathered, after 

 great research, by one of the authors of this paper. The search has 

 been systematically pursued since 1862, when the first fossil of the 

 Menevian group was described by Mr. Salter from this neighbour- 

 hood ; and the labour has chiefly fallen upon Mr. Hicks, who resides 

 at St. Davids. He has literally not left a stone unturned to find the 



