66 Reviews — Dr. Traqiiair on Silurian Fishes. 



previously has only been published in Japanese journals, more 

 easily accessible. The subject-matter is mainly confined to the 

 enumeration of occurrences ; and for museum curators, puzzled by 

 Japanese locality names, the paper will be very useful. Longer 

 descriptions are given of quartz, topaz, and felspar, these minerals 

 being represented in Japan by specially fine ci'ystals. 



S, E "V I E "V^ S. 



I. — De. Tuaquair on Silurian Fishes. Eeport on Fossil Fishes 

 collected by the Geological Survey of Scotland in the Silurian 

 Eocks of the South of Scotland. By Eamsay H. Traquair, 

 M.D., LL.D., F.E.S. Trans. Eoy. Soc. Edinb., vol xxxix, 

 pp. 827-864, pis. i-v. (December, 1899.) 



DE. TEAQUAIE'S new memoir on the Upper Silurian fishes of 

 Southern Scotland is the most valuable contribution to our 

 knowledge of Palgeozoic Ichthyology which has been made for many 

 years. It is of fundamental importance not only as describing with 

 tolerable completeness the exoskeleton of several organisms which 

 have hitherto been known only by indeterminable isolated frag- 

 ments ; it also records for the first time a series of well-ascertained 

 facts in reference to the primitive mode of development of the 

 dermal armour of the Vertebrata. Moreover, it is a work which 

 could not have been accomplished, or at least have been done 

 in a thoroughly trustworthy manner, by anyone less skilled in 

 the observation and interpretation of Palteozoic fish remains than 

 Dr. Traquair himself. Most of the fossils are very obscure, and 

 can only be understood after long-continued study and repeated 

 comparisons. Any geologist or biologist who casually examines 

 them will feel gratitude to the painstaking author, whose patience 

 and unwearied zeal have enabled him to obtain so much information 

 from them as is contained in the beautiful memoir now before us. 



The specimens in question were discovered by Messrs. Macconochie 

 and Tait, collectors to the Geological Survey of Scotland, in the 

 Upper Ludlow and Downtonian beds in the neighbourhood of 

 Lesmahagow, Lanarkshire. The thin bands in which they occur 

 consist of hard, grey, flaggy shale ; and in most cases the actual 

 substance of the fossils seems to be preserved. 



The two first genera described are considered to be primitive 

 Heterostraci or Pteraspidians, in which the dermal armour consists 

 of isolated shagreen-like granules, not yet fused into plates. They 

 constitute the family Coelolepid^ of Pander, which was known 

 only by the detached dermal granules until a year ago, when 

 Dr. Traquair published a foretaste of his results in the description 

 of Thelodiis Pagei from the Lower Old Eed Sandstone of Forfarshire. 

 Two new species of Thelodus {T. scoticus and T. planns), from the 

 Upper Silurian, are now described and figured. The head and 

 trunk are completely covered with a dense layer of the little 

 shining, quadrangular granules, which have long been familiar to 



