ON CATALOGUES OF SPECTRAL RAYS. 249 



Note. — Since the preceding Eeport was presented, additional information 

 has been obtained from various sources, particiilarly by means of a detailed 

 examination of the Labyrinthodont fossils in the Museum at Warwick. The 

 nature of the mandibular articulation of Mastodonsaurus, for example, is 

 more clearly revealed by undescribed specimens in the Warwick collection 

 than by any of the Wiirtcmberg fossils. A special paper, containing an 

 account of the results arrived at, wiU shortly be published. Some notice of 

 the structure of the osseous ear-chamber, as exliibited by the large skull of 

 Capitosaurus from the Keuper sandstone of Wiirtemberg, should have been 

 included in the Report. The essential facts are given by Quenstcdt (Die 

 Mastodonsaurier im griinen Kcupersandsteine Wiirtembcrg's sind Batrachier, 

 p. 14, t. ii. fig. 1, and t. iii. figs. 16, 18). On a future occasion the Com- 

 mittee hope to give the results of a microscopic examination, now in progress, 

 of the teeth of various Labyrinthodont genera. 

 January 1874. 



EXPLANATION OF PLATES I.-III. 



Plate I. 



Skull of Loxomma (restored). The contours are chiefly taken from a fine uncompressed 



specimen in the possession of Mr. George Maw, F.L.S. 



Plate IL 



Fig. \. Side view of skull oi Loxomma. 



2. Posterior extremity of mandible of Loxomma, showing the absence of a post- 



articular process (Eeport, p. 237). 



3. Posterior extremity of mandible of Biadetognathus, showing a well-deTeloped 



post- articular process. 



Plate III. 

 Fig. 1. Atlas of Mastodonsaurus, front view (Paliiontologie Wiirtembergs, t. v. fig. 4). 



2. Eestored cervico-dorsal vertebra of Mastodo7tsaitrus, seen from before, showing 



the articular facet upon the centrum (Eeport, p. 239). 



3. Dorsal vertebra of Fteroplax (?), seen from behind (Hancock and Atthey, Nat. 



Hist. Trans. Northumberland and Durham, vol. iii. t. ii. fig. 2). The vertebra 

 is slightly restored, and shows the two facets upon the transverse process (Ee- 

 port, p. 239). For comparison of vertebra of Anthracosaums (?), see Huxley, 

 ' Quart. Journ. Geol. Soc' vol. xix. p. 63. 



4. Antero-posterior section of vertebral centra, (a. Mastodonsaurus, b. Pteroplax, 



c. Pholidcrpeton.) 



Report of the Committee appointed to construct and print Catalogues 

 of Spectral Rays arranged upon a scale of Wave-7iumbers, the 

 Committee consisting of Dr. Huggins, J. N. Lockyer, Professor 

 Reynolds, Professor Swan, and G. Johnstone Stone y (Reporter). 



The Committee, appointed to construct and print catalogues of sj^ectral lines 

 arranged upon a scale of wave-numbers, had hoped to i)resent the catalogue 

 of solar lines, and of a large number of metallic lines, at the present Meeting 

 of the Association ; but a delay having arisen about the engraving of the 

 maps which should accompany the catalogues, they have not been able to go 

 to press in sufficient time. 



The whole of the solar spectrum is now ready for the printer ; and the 

 reduction of those positions of metallic lines which Thale'n determined by the 



