Causes which retard Zoological Knowledge. 303 



tions to their internal organization as unfolded by zootomy, he 

 ■would have added greatly to the cumulative mass of solid in- 

 formation, and would have spared himself much unproductive 

 labour. 



We have, nevertheless, perused the treatise with both profit 

 and satisfaction ; it not only shows considerable research, but 

 convinces us of the increasing taste for similar pursuits in Eng- 

 land. 



With these preliminary observations we propose to note a 

 few of the inaccuracies and oversights which are but too evident 

 to the practical herpetologist. There is occasionally displayed 

 a looseness of style, which might have been dispensed with in a 

 work strictly scientific ; speaking of the class reptilia, he says, 

 " tJie young are like the mother." Now we have raised numbers 

 of these little creatures in our own garden, and can assure Mr. 

 G. that the young not unfrequently betray a strong likeness to 

 the father/ The characters which distinguish some of his ge- 

 nera, are in reality no distinction whatever; thus his genus 

 " Chelys," at page 7, is designated by marks equally applicable 

 to the very different genus Trionyx. 



He sometimes founds specific distinctions, on slight difference 

 in colour, or some insignificant markings : see for example his 

 Emys decupata, compared with E. serrata ; whilst in other in- 

 stances, species, perfectly well characterized by recent authors, 

 are confounded in the synonyma : thus Testudo elephantopus, is 

 quoted as synonymous with T. indica — the former differing in 

 the number and form of the marginal plates, in the presence of 

 a nuchal plate, and in the totally different direction of the poste- 

 rior marginal plates — not to mention other peculiarities observ- 

 able in the head and integuments. We consider these species to 

 be as distinct in organization, as they are distant in their habits. 

 After having stated that the marginal plates of tortoises re- 

 present analogically the costal cartilages of mammalia ; Mr. G. 

 remarks, " the testudo areolata (Thunb.) is apt to vary in the 

 number of dorsal and marginal plates," which is to admit a vari- 

 ation in the number of ribs and of their cartilages ; a difference 

 of this nature, we think, rather points to specific distinction; 

 much more so, indeed, than the " sculpture of its shields, and pe- 

 culiar scaling of the animal." Vide page 13. 



The Testudo pusilla, (Linn.) Mr. Gray describes for the 



