071 the Mollusca of Europe and North America. 375 



long as the nasal. The single praeocular reaches to the upper 

 surface of the head, and is in contact with the vertical. Three 

 postoculars. Eight upper labials, the fourth and fifth entering 

 the orbit. Temporals 1 + 2 + 3, but rather irregularly an-anged. 

 A groove (of black colour) between the temporals and labials. 

 Ventralsl87; subcaudals 135. Brownish, some of the dorsal 

 scales with a blackish edge ; tail with a black line on each 

 side, along the outer margin of the subcaudals ; sometimes 

 another pair of less distinct blackish lines along the back of 

 the tail. Brownish yellow below, with or without irregular 

 powdered spots. 



Total length 33 inches, of which the tail takes 13 inches. 



Southern parts of Madagascar. 



XLIV. — Reply to Professor VerrilVs " Remarks on certain 

 Ei-rors in Mr. Jeffreys' s Article on the Mollusca of Europe 

 compared loith those of Eastern North America.''^ By J. 

 GwYN Jeffeeys, F.R.S. 



I HAVE been hitherto prevented by various engagements from 

 noticing Prof. Verrill's remarks on the above article, which 

 was published in the ' Annals ' of last October. 



Although I would rather invite than deprecate a fair criti- 

 cism of this or any other publication of mine, I cannot lielp 

 regretting that the present critic has not adopted the same 

 style of courtesy which so agreeably characterizes his scientific 

 countrymen. 



I do not admit the wholesale charge of " errors " and " mis- 

 takes " which is so freely made in his " Remarks," nor that it 

 was incumbent on him personally to disclaim my views. Let 

 them be examined by some competent authority. 



The errors attributed to me are those which relate to geo- 

 graphical and local distribution, to the difference of certain 

 species, and to the nomenclatm*e of two other species. 



The question of geographical distribution, involving that of 

 migration, is a subject which cannot be hastily disposed of ; 

 but Prof. Verrill's idea tliat the land and fresliwater shells 

 which are common to tlie Old and New Continents may have 

 originated in America and thence crossed to Euro])e "in the 

 direction of the prevailing currents and winds " is more 

 ingenious than probable. Currents and winds are not the kind 

 of agency we should expect for the migration of such animals. 

 However, I will not offend his national susceptibilities any 

 further. 



With regard to local distribution I can only repeat that I 



