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, 

 " the 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 t4> 

 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 areol at a (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 / 



