242 



Mr. G. A. Boulenaer on (7ie Ixaces and 



most a very lew, when large scries can be exatnined, or 

 ■without reference to the data available tluougli tlie labours 

 of other investigators, is unfair to tliose who make use of 

 works written on such lines. Systematics, if scicntitic, must 

 take into full consideration the exceptional, aberrant, or 

 annectant specimens, so often passed over wiihout a word, 

 though of 80 great an importance from the taxononiic an. I 

 evolutionary points of view. It does not matter if tiiereby 

 our definitions are obscured, the object to be attained is to 

 depict the true state of things in Nature. 



To the four forms which 1 have previously * distingui^-hed, 

 as torma (i/pica, var. ridibunda, Pall., var. Iesson(i\ Canier., 

 var. chinensis, Osb., 1 have recently added a fifth, var. 

 .saharica'f, founded on sj)ecimens obtained by Dr. E. Harfert 

 in the far interior of the Algerian Sahara (El Goha, Tediket 

 oases), a small race nearly related to the var. rfdibuvda of 

 the northern parts of Algeria but differing in the shorter 

 libire, constantly less than half the length of head and body 

 and not overlapping when the limbs are fohled at right 

 angle.s to the body ; the membrane between the toes is very 

 deeply notched, so much so that many specimens may be 

 described as having the foot only three-fourths webbed. 



T//e Vomerine Teeth. 



I have never seen these teeth in two series on the round 

 or elliptic bony bases that bear them, as described and 

 figured by Fatio+. They form a single series, com])osed of 

 3 to 8 ; in exceptional cases I find only 1 or 2 teeth (speci- 

 mens of the typical Ibinifroni St. IMalo, Brussels, and Basic). 

 Leydig§ gives the number 3 as normal, but he cannot have 

 examined many specimens, those on which he drew up his 

 desciiption being ]nubably mostly of the var. lessona', as the 

 figure of the loot given in his book indicates, and this number 

 is very frequent in the variety in question, although it may 

 rise to 5. In 8 frogs c i the typical form IVom Basle I find 

 oidy 2 to 4 teeth, whilst in 35 fron) other paits of Switzer- 

 land, from France, ard from Germany I count 3 to 7, 4 to 6 

 being the usual number ; 1 have also seen a toothless 

 sjjecimen from Vienna. In about 30 specimens of the var. 

 ridi/naida from Germany and Austria I count usually 4 to 6 

 teeth ; 3 specimens have only 3, one has 7 on one side and 



* Proc. Zool. Soc. 189], p. 374, aud Taill. Batr. Eur. p. 270 (1898). 



t Nov. Zool. xx. 1913, p. 84. 



J Vert. Suisse, iii, p. 313. p]. v. ti^r. 7 (1872). 



§ An. K'ltr. iJeiitsclil. y. 112, pi. iii. jig. 20 (1877). 



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