98 ANNALS OF SCOTTISH NATURAL HISTORY 



2. There is a median opening or ring, surrounded with 

 cirri, and presumably nasal, in the front of the head. 



3. There are neither jaws nor limbs. 



4. The rays which support the caudal fin -expansion, 

 apparently springing from the neural and haemal arches, are 

 dichotomised (at least the neural ones), as are the correspond- 

 ing rods in the Lamprey, 



And if Paltzospondylus be not a Marsipobranch, it is quite 

 impossible to refer it to any other existing group of Verte- 

 brata. 



LITERATURE OF PALJEOSPONDYLUS. 



1. Traquair, R. H., "On the Fossils found at Achanarras Quarry, 



Caithness," Ann. and Mag. Nat. Hist. (6), vol. vi. (1890), 

 p. 485. 



2. Woodward, A. Smith, Catalogue of the Fossil Fishes in the British 



Museum, part ii. (1891), p. 553. Reference to the above. 



3. Howes, G. B., " On the Affinities, Inter-relationships, and 



Systematic Position of the Marsipobranchii," Trans. Biol. 

 Soc. Liverpool^ vol. vi. (1891). 



4. Woodward, A. Smith, "The Forerunners of the Back-boned 



Animals," Natural Science, October 1892, pp. 597-599, 

 Fig. i. 



5. Traquair, R. H., " A further description of Palczospondylus Gunni" 



Proc. Roy. Phys. Soc. Edin., vol xii. part i. (1893), pp. 87-94, 

 Plate I. Reviewed by Mr. Smith Woodward in Natural 

 Science, August 1893, p. 128, and in Geol. Mag. (3), vol. x. 

 p. 471. 



6 Dawson J. W., Salient Points in the Science of the Earth (London : 

 1893), pp. 285, 286. With a figure. 



7. Traquair, R. H., "A still further Contribution to our Knowledge 

 of Palceospondylies Gunni" Proc. Roy. Phys. Soc. Edin., 

 vol. xii. pp. 312-321, Plate IX. 



EXPLANATION OF PLATE III. 



{For permission to reproduce this plate, the author is indebted to the Council of the 



Royal Physical Society.) 



The lettering is uniform throughout all the figures, t.p., Anterior or trabeculo- 

 palatine part of the cranium ; p. a., posterior or parachordal part ; a., lobe divided 

 off from the anterior part ; b. , anterior depression or fenestra ; c., posterior depres- 

 sion or fenestra ; ., nasal ring ; v.c., cirri of the ventral margin of the ring ; I.e., 

 long lateral cirri ; d.c., cirri of the dorsal margin ; v., vertebral centra ; x., post- 

 occipital plates. 



Fig. i. Head of Palaospondylus Gunni, seen from the ventral aspect, and 

 showing the presumed nasal ring with its cirri. The rest of the cranium is eroded. 

 Magnified five diameters. 



