CRUSTACEA MAI,ACOSTRACA. II. 



founded families, Apseudidae and Tanaidae, and pointed out their distinguishing characters; he established 

 nine new genera (only five had been previously described); he enumerated nearly all species described 

 from any ocean, and he added short descriptions of all species seen by him, redescribing a good 

 number of species already made known and establishing twenty-three new species. He enumerated 

 in all 3 genera and 14 species of the Apseudidae, n genera with 46 species of the Tanaidae, in all 

 14 genera with 60 species. But 4 species among the Apseudidae were nomina nuda given bv Norman, 

 and Sars had overlooked a single species of Apseudes established by Willeinoes-Suhm and two species 

 of Tanaidae established respectively by Nicolet and Bate. The result is that in 1884 59 species (not 

 counting mere synonyms) of Tauaidacea had been established. 



In 1S86 G. O. Sars published his important paper: Middelhavets Saxisopoder (Isopoda chelifera), 

 which contains elaborate descriptions with numerous excellent illustrations of seventeen species, all briefly 

 described but not figured by him in 1880. And in his splendid work : An Account of the Crustacea of Norway, 

 Vol.11, Isopoda (the parts on the Tauaidacea were edited in 1896 — 97) Sars published new descriptions and 

 eighteen plates with figures of the Norwegian Tauaidacea, in all 28 species. By the three papers enumer- 

 ated Sars has laid down a very broad foundation for future study and illustration of the animals, and 

 he has done far more for the furtherance of our knowledge of the order than any other author. 



Since 1881 about twenty-four zoologists have published descriptions of new species, sometimes 

 besides of new genera, of Tanaidacea. Among these prominence must be given to the two English 

 zoologists A. M. Norman and T. R. R. Stebbing, because in a valuable paper (On Crustacea Isopoda . . . 

 1886) quoted several times in this report they gave good descriptions with numerous figures of 

 17 species (1 valid new genus), 13 of which were new and the majority even deep-sea forms; in other 

 papers each of these two authors has described and figured some other forms. — In the Challenger 

 Report Vol. XVII (1886) F. E. Beddard established 4 new genera and 10 new species, most of them 

 interesting antarctic or deep-sea forms; unfortunately his figures are somewhat poor. — A. Dollfus has 

 published preliminary descriptions, with some figures, of about 14 valid new species and 1 new and 

 valid genus; in several papers published in later years Miss Harriet Richardson has established 2 new 

 genera and several new species, mostly American. 



In order to arrive at a fair idea of our knowledge of genera and species established before 

 the middle of 1912 I have inspected the Zoological Records since 1877 and besides looked over the vast 

 majority of the papers. I have attempted to count the genera and species hitherto established, excluding 

 of course the synonyms, but it was impossible to arrive at absolute certainty as to the number of 

 species, because in a few cases it cannot be made out whether a species is valid or ought to be 

 cancelled as a synonym, and some few species have been so poorly described that they can scarcely 

 be recognized with any certainty. But I am sure that the following numbers are nearly correct. 



The family Apseudidae comprises 8 genera: Apseudes Leach with 28 species, Apsntdopsis Norm, with 

 2 species, Parapsrudcs Sars with 3 species, Sphyrapus Norman with 5 species, Typlilapscudrs Bedd., Lciopits 

 Bedd., Kalliapseudes Stebb. and Pagurapseudes Whitelegge, each with a single species. In all 42 species. 



The family Tanaidce comprises the following genera: Neotanais Bedd. (Alaotaiiais Norm. X: 

 Stebb.) with 5 species, Tanais H. M.-Edw. with 17 species, Leptoclirlia Dana with 16 species, Hctcrotanais 

 G. O. S. with 9 species, Paratanais Dana with 9 species, Nototanais Richardson with 3 species, Typhla- 



