A. REVIEW OP THE PROGRESS OF NORTH AMERICAN IN- 

 VERTEBRATE PALEONTOLOGY FOR 1884. 



By John Belknap Maecou. 



In this work I have endeavored to collect the titles of all of the works 

 on North American invertebrate palsBontology published during the 

 past year. An attempt has been made to give a brief idea of the con- 

 tents of each work, the new genera and species described, and the general 

 conclusions of the authors. The alphabetical arrangement by authors 

 seemed, after a good deal of thought, the best method of arrangement 

 and has consequently been adopted. The explanatory notices are placed 

 after each title. The work I hope will prove useful, and I will be glad 

 if those who notice them will call my attention to any omissions. 



Ami, H. M. — Notes on TriartJms spinosus Billings. (Trans. Ottawa 



Field Naturalists' Club, No. 4. Ottawa, 1883.) 



Interesting notes on this Trilobite with two figures, one a copy of 

 Billings's, the other original, with some of the furrows and grooves on 

 the occipital segment imperfectly figured. 



Beecher, C. E. — Ceratiocaridce from the Chemung and Waverly Groups 

 at Warren, Pa. (Rep. of progress, P. P. P., 2d Geol. Surv. Penna., 

 pp. 1-22, pis. i and ii, Harrisburg, 1884.) 



A very interesting imper on a grouj) of which but little is known. 

 Gives descriptions of two new genera, Elymocaris and Tropidoearis, El. 

 siliqua n. sp. and T. Mcarinata, T. interrupta, T. alternata n. sp., and 

 also a new species of Echinocaris, E. socialis u. sp. He also redescribes 

 and gives good figures of E. punctata Hall. The figures and descrip- 

 tions are excellent 5 a short bibliography of the subject is also given. 



Billings, W. R. — Notes on, and description of, some fossils from the 

 Trenton Limestone. (Trans. Ottawa Field Naturalists' Club, No. 4. 

 Ottawa, 1883.) 



Describes a new species, Heterocrinus hellevillensis, with good figures. 

 Gives a good illustration showing the arms of Dendrocrinus jewettii 

 Billings, 1859 ; he estimates their number at least at forty. Describes 



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