156 REVIEWS NEW SPECIES OF PALEOZOIC FOSSILS. 



judge from Prof, Hall's figures and descriptions, for no definition of the 

 genus is given, it appears to us that the species here included, might 

 be legitimately arranged under McCoy's Athyris (Spirigera, d'Orb.); 

 or, in part, under Terebratula, in which genus, as the type of a group 

 of Palesozoic Terebratulse without deltidium, we would place the Sem- 

 inula of McCoy. The texture of the shell in Hall's Meganteris is not 

 stated. In the work now under notice, little more than a brief enu- 

 meration of the proposed new species could be expected : the author's 

 object being simply, as before observed, to ensure a priority of publi- 

 cation. It will add however, very much to the utility of the volumes 

 of the Palaeontology about to appear, if a definition of each genus be 

 given, and a distribution of the genera into families be at the same 

 time adopted. Comparisons will in this manner be much facilitated, 

 and an air of greater completeness imparted to the work. These 

 definitions are not only essential in the case of new genera, but they 

 are equally necessary with regard to genera already established ; be- 

 cause in adopting one another's genera, palaeontologists are rarely 

 agreed as to the precise limitation of these. With the progress of 

 discovery, indeed, the necessity of modifying earlier definitions will, 

 from time to time, unavoidably arise ; especially as it is above all 

 things desirable to keep down the array of new names as much as 

 possible, and to guard strictly against the adoption as generic, of 

 characters of a specific value only. In Palaeontology — and in the 

 Class Brachiopoda more particularly, where the most essential cha- 

 racters, for instance, are so rarely to be observed — the greatest caution, 

 for the sake of those who come after us, is in this respect, necessary. 

 With regard to specific forms also, we trust the day is not far distant, 

 when palaeontologists will be willing to admit that a merely relative 

 difference — a difference, for example, that cannot be properly appre- 

 ciated without the aid of figures — is not a sufiicient warranty for the 

 foundation of a second species. These remarks, however, are not to 

 be applied to the author of the work of which we now take leave. 

 Our readers, if at all acquainted with the subject, will know well, that 

 if Professor Hall, in accordance with a system too much in vogue, had 

 chosen to turn " species-iiiaker," he might have given us twenty new 

 species, where he has given us one. For the exercise of this discrimi- 

 nating judgment, palaeontologists generally owe him their best 



thanks. 



E. J. C. 



