﻿222 ANT1ARCHA. 



ornament both of the ventral plates and caudal scales is 

 shown in impression. Purchased, 1861. 



(iv.) Cromarty. 



19052, 19055, 19059. Three imperfect examples of the trunk, 

 ventral aspect, the first also showing traces of the tail, 

 and the third, of the head. Purchased, 1845. 



19804 a. Imperfect specimen displaying the inner aspect of the dorso- 

 lateral and median dorsal plates, and characteristic por- 

 tions of the expanded appendages. In the orbital opening 

 the " os dubium " is distinctly separated from the right 

 orbital plate, and there is a trace possibly of an anterior 

 plate in advance of the former. The scales of the tail are 

 observed to be tuberculated. Purchased, 1845. 



47870. Much crushed trunk and appendages, in counterpart, showing 

 ornamentation. Purchased, 1877. 



Pterichthys rhenanus, Bey rich. 



1855. Physichthys hoeninghausi, H. von Meyer (errore), Palaeontogr. 

 vol. iv. p. 80, pi. xv. fig. 7. [Anterior median dorsal plate ; Cam- 

 bridge Museum, Mass.] 



1877. Pterichthys rhenanus, E. Beyrich, Zeitschr. deutsch. geol. Gesell. 

 vol. xxix. p. 751, pi. x. 



Type. Dermal armour of trunk ; Berlin Museum. 



Inferior surface of carapace broadly ovate. Anterior median 

 dorsal plate as broad as long, extremely elevated, the longitudinal 

 ridge bent at a right angle slightly behind the middle point; posterior 

 median dorsal plate two thirds as long as the anterior median. 



Form. Sf hoc. Devonian : Gerolstein, Eifel. 



Xot represented in the Collection. 



Dermal plates of Antiarcha (and probably other Chordate types), 

 too imperfect for satisfactory determination, have also been assigned 

 to Pterichthys under the following names : — 



Pterichthys arenatus, L. Agassiz, Poiss. Foss. V. G. R. (1845), 

 p. 133, pi. xxx. a. fig. 3. — Devonian ; St. Petersburg. 



Pterichthys cellulosus, C. H. Pander in A. von Keyserling, Beise 

 in das Petschoraland (1846), p. 292 a.— Devonian ; Pet- 

 chora Land, N.E. Russia. 



Pterichthys elegans, C. H. Pander, Monogr. Foss. Fische Silur. 



