96 REVIEWS 



"The present work is a start toward the publication of a series of 

 monographs which it is hoped may eventually cover all the groups of 

 organisms whose fossil remains are preserved in these formations." 

 The scope of the present work is practically that of the Mississippian 

 rocks of Illinois, Missouri, and Iowa, the typical Mississippian section. 



All the genera and all the species are described and abundantly 

 illustrated. More than that, all the old descriptions of species have been 

 rewritten, "so that the usage of terms is uniform throughout." 



There are 62 genera and 297 species described. Of this number 4 

 genera and 80 species are new to science. The limits of the genera and 

 species are closely drawn throughout. However, they are no more 

 closely drawn than is necessary to give a clear understanding of the 

 anatomical relationships and to give proper stratigraphic value to a 

 species. This does not necessarily imply that all the genera are limited 

 to a few species, since there are 44 species of the genus Spirifer recog- 

 nized as valid and described from the Mississippian rocks of the Missis- 

 sippi Valley basin. The list of species described as new is given herewith, 

 together with the critical characters of the new genera: Lingula louisi- 

 anensis, Leptaena convexa, Schuchertella fernglenensis, Schellwienella 

 crenulocostata, S. chouteauensis , S. planumbonum, S. altemata, S. burling- 

 tonensis, Streptorhynchus tenuicostatum, Chonetes miss our iensis, C. 

 chesterensis, Productella sublaevis, Productus mesicostalis, P. crawfords- 

 villensis. 



The genus Echinoconchus was erected for those species of Productus 

 with "more or less sharply differentiated concentric bands which com- 

 monly grow broader in passing from the beak to the outer margins, each 

 band bearing numerous, crowded, fine, appressed imbricating spines, 

 either subequal or unequal in size, which are produced from elongate, 

 node-like bases." Productus punctatus is the genotype. It so happened 

 that a work entitled The British Carboniferous Producti, the first part, 

 by Ivor Thomas, was issued on June 6, four days prior to the issue of 

 Weller's monograph. In this memoir, 1 treating of the first part of the 

 genus, apparently the same group of shells are gathered under the genus 

 Pustula. If they are the same, this term, having priority, will be used 

 instead of Weller's term given above. The genus corresponds with 

 Waagen's section IV, Fimbriati, in a general way, as published in the Salt 

 Range Fossils, Brachiopoda, p. 671. The species referred by Weller to 

 the genus are: P. altematus, P. genevievensis n.sp., P. biseriatus, P. 

 morbilianus. 



1 Memoirs Geological Survey, London, I, Parts 2, 4, June 6, 1914. 



