Bibliographical Notices, 511 



Ponnaylvania which deBorvos attention, not only from CurcinologiKta 

 but from all who arc iiitcrenlcd in the wider problems of zool()j,'y. 



Ill tlio Krst i».irt of the memoir the autlior discusses the syHtomatic 

 characters of the t'urms found within tlie limits of the Stiite. Seven 

 species and one variety are recognized, and their variations are set 

 forth in great detail. Dr. Ortmann's conclusions as to the limits of 

 the sjjccies are not to bo lightly disputed, were it only on account 

 of the vast amount of material — between two and three thousand 

 specimens — at his disposal. Further, his familiarity witli the living 

 animals — most of tlie material -was collected ])y himself — gives him 

 a great advantage over the mere museum species-maker. 



The next section deals at length with the occology and distribution 

 of the various species. Especially interesting are the details given 

 of the habits of the " chimney-builders " — the burrowing species 

 which are so called from the chimney-like piles of mud thrown up 

 at the mouths of their burrows. These species are found often at 

 considerable distances from open water, burrowing down to reach 

 the ground-water, and their chimneys are sometimes so numerous 

 as to " hamper farming operations by interfering with the harvesting 

 machines, clogging and ruining them " ; elsewhere they were 

 observed " coming up eveii between the railroad ties of the Mor- 

 gantown and Kingwood Railroad." The distribution of the species 

 within the State is illustrated by coloured maps, and it is shown that 

 many of the facts cannot be correlated witli the existing physio- 

 graphical conditions. An exidanation is sought in past changes in 

 the configuration of the country and esjiecially of the river-systems. 

 How far the author's speculations as to the pre- and post-glacial 

 migrations of the various species are justified is a question which 

 can only be answered by local research, but they are certainly 

 suggestive and stimulating. 



Tlie life-histories form the subject of the following section, and 

 remarkable differences are shown to exist between the species in 

 this respect. Two main types of life-history are distinguished, a 

 " warm water " type characteristic of the species found in the larger 

 rivers, and a " cool water " type shown by the species found in 

 mountain-streams. In the former a delinite seasonal cycle is 

 observed, mating taking jdace in the autumn and spawning in the 

 spring, while the cool water species breed at all seasons of the year. 

 Some details are also given of the remarkable alternation of breeding 

 and non-breeding jHiases which, as P'axon discovered, gives rise to 

 the so-called " dimorphism "' of the males in the American Crayfishes. 

 A similar phenomenon Ims recently been described by Mr. (t. Smith 

 in certain crabs and may possibly bo found to occur in other 

 Crustacea. 



After a short section dealing with the economic aspects of the 

 Crayfishes, the memoir concludes with a discussion of some current 

 theories of evolution in the light of the fact« set forth. Many of 

 the points touched on arc of a highly controversial nature, and the 

 arguments cannot be summarized liere. It may be said, however, 

 that Dr. Ortmann sees no evidence of " mutation '* in the origin of 

 species (and here, we believe, many systematic zoologists will agree 



