36 Reviews — R. Etheridge Jim., Palceozoic Fossils ofK.S. Wales. 



them at least — with the third thoracic segment drawn out into a long 

 pleural spine on either side, giving them a most weird appearance 

 (these are occasionally curled round, as in Olenelhis Gllberti). In 

 Mesonacis Vermontana, the abdomen is elongated into 12 or 13 

 segments, with a powerful median dorsal spine rising from the 

 proximal segment, and reaching to the end of the body ; in 

 31. asaphoides there are five of these spines ; in Holmia Bioggeri 

 spines are present down the centre; the nuchal median spine being 

 equal in length to nearly seven of the body segments. 



This form is no doubt most nearly related to Professor Lapworth's 

 Olenellus CaJlavei, but there are well-marked differences between them, 

 when carefully compared, both in the head-shield, body-segments, 

 and spines. Olenellus (Mesonacis) Mickwitzii and O. (Holmia) 

 Kjerulfi, the former a Russian form and the latter from Sweden, 

 suggest new departures in spines and tubercles and a facies diverging 

 towards Paradoxides of the Middle Cambrian, but with marked 

 differences. The spine, on the axis of the Russian form, reminds 

 one of the genus Cyj/JMSpis. 



There is a common family-likeness in all these Olenelli, but they 

 run through a great variety of form, amounting in some probably to 

 generic value, as pointed out by Mr. Walcott. This is strikingly 

 the case if we compare his Olenellus Thompsoni with Olenellus 

 (Holmia) Kjeridji, and Olenellus Gilberti with Olenellus (Mesonacis) 

 Vermontana and 0. (Mesonacis) MicJcioiizii. 



Sixty-one pages are occupied (pp. 597-658) with carefully pre- 

 pared Notes on the genera and species of the fauna of the Olenellus 

 Zone, and the work concludes with what all works should possess, 

 namely, a good index. 



We heartily congratulate the author upon having had the honour 

 to bring together so admirable a Monograph upon a new or but 

 little understood formation, which has apparently so remarkable a 

 geographical range, and possesses such a well-marked fauna where- 

 ever it has been observed. Such discoveries in the geology and 

 paleontology of the oldest PalsBozoic rocks may well serve as an 

 incentive to future workers, and clearly show that much yet 

 remains to be done in order to complete our knowledge of the 

 fauna of these ancient seas. 



II. — A Monograph of the Carbon ifekous and Permo-Carbon- 

 iFEROUs Invertebrata OF New South Wales. Part I. 

 Coelenterata. By R. Etheridge, jun., Paleeontologist and 

 Librarian to the Geological Survey of New South Wales, etc. 

 Memoirs of the Geological Survey of New South Wales. 

 By C. S. Wilkinson, F.G.S., etc.. Geological Surveyor-in-Charge. 

 4to. pp. ix. 64. Pis. L-XL (Sydney, 1891.) 



THE Geological Survey of New South Wales, with the view of 

 extending a knowledge of the coal-bearing formations in that 

 colony, has determined to publish fresh descriptions of the inverte- 

 brate fossils in these rocks, which have been collected by the 



