288 Correspondence — E. Ray Lanhester. 



geological books I have access to ; so the specific name of the Eyho- 

 dus from our Carboniferous formations must for the present be in 

 abeyance. 



Newcastle-on-Tyne, W. J. Barkas, L.E.C.P.L. 



April 2ith, 1874. 



MAGISTER SCHMIDT ON THE SHIELDS OF PTERASPIS AND 

 SCAPHaSPIS} 



Sir, — I have just received, by the kindness of Herr Magister 

 Schmidt, a paper by him entitled, "On Pteraspids in general, and on 

 Pteraspis Knerii in particular," which, I dare say, may come to the 

 notice of some of your readers. Herr Schmidt reiterates the view 

 which I have previously discussed as to the nature of the shields for 

 which I proposed the genus Scaphaspis. Let me again say here that 

 no evidence loliatever is adduced by Herr Schmidt in support of the 

 notion that Scaphaspis is the ventral shield of Pteraspis and Cyath- 

 aspis. That such a connexion is a possibility, I do not mean to deny ; 

 but with a very much larger number of specimens to study than 

 Schmidt or Kunth have had, and with the same hypothesis present 

 in my mind, I have been unable to find justification for its adoption. 



With regard to the Galician Pteraspis, I have already stated in the 

 Geological ]\Tagaztne,^ after examining specimens from this locality 

 in Vienna, I was led to doubt the specific distinctness of the Pt. 

 Knerii. The Viennese specimens come very close indeed to Pteraspis 

 rostratus and Scapliaspis Lloydii. The specimen of a disc now figured 

 by Schmidt comes so close to that of Pt. Crouchii that it must prob- 

 ably be assigned to that species. Magister Schmidt is mistaken in 

 assuming an exclusive association of Pt. rostratus with Sc. rectus. 

 On this matter I should be glad if some of my friends at Ludlow 

 and elsewhere in the Cornstone area would give their experience. 



The asserted presence of bone-lacunte in the Heterostraci certainly 

 cannot be accepted on such evidence as that which Herr Sclimidt 

 adduces. Either his sections do not show definite bone-lacunae or 

 they have been very inadequately lithographed. 



Naples, A2Jril lath. E. Eay Lankesteb. 



1 For Magister Schmidt's letters see Geol. Mag. 1873, Vol. X. pp. 152 and 330- 



2 For Mr. Lankester's reply see op. eit. Vol. X. pp. 190 and 478. 



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