1 882.] Progress of Invertebrate Palceontology, etc. 887 



may perhaps best be accounted for by conceding to the group a 

 normal dentition of 3-3 . 6)3 which by consolidation or suppression 

 of teeth would cover all the forms yet investigated. 



The species of Chitonidae found in deep water on the American 



coast are enumerated, and the paper 1 concludes with a scheme of 



classification of the Docoglossa brought up to date from that 



proposed by the writer twelve years previously. 



(To be continued.) 



PROGRESS OF INVERTERRATE PALAEONTOLOGY 

 IN THE UNITED STATES FOR THE YEAR 18S1. 



AX7E have not to record the death of any worker in invertebrate 

 " " palaeontology during the past year, and the names of those 

 who have published the results of their investigations during 

 1 881, are mostly well known through their previous labors. The 

 following account of work published during the past year is not 

 really the measure of the amount that has been done ; for some 

 of those who are most deeply engaged in the work, have pub- 

 lished very little within that time. Those gentlemen have kindly 

 kept me informed of the progress of the work they have in hand, 

 and mention is made of some of these in the following para- 

 graphs : 



Mr. S. W. Ford has continued his studies of the primordial 

 fauna, and has published a very interesting paper on the " Em- 

 bryonic forms of Trilobites from the Primordial rocks of Troy, 

 N. Y., in the American Journal of Science, Vol. xxn, pp. 250-259, 

 with 13 woodcuts. Also " Remarks on the genus Obolella," in 

 Vol. xxi, of the same journal, pp. 131-134. with 5 woodcuts. 



Professor James Hall informs me that " no reports of the New 

 York State Museum having been printed for the past three years," 

 he has a large amount of work awaiting publication. As these 

 works may be expected to appear soon, only brief reference need 

 be made to them now. 



