( 22(i ) 

 1-'. Peradorcas (i;-. u.) conciuua (imilil. 



(J lino, II (i4. ? lir>s, li:)'.l. Nellie Civrk. And Iwn yiiniiL;-, Miiliilielled. 



In granite nuiges. 



Ul> to the date of the CatiUogue of Jlai'suiiials the only specimen of 

 " refroycile " concinna avaihable for examination was the type, and, peculiar as 

 the dentition seemed, it was imjiossible to determine whether or not this sinjile 

 sperimen was abnormal.* Now, however, the stndy of Mr. Tnnney's material, 

 combined with a number of skulls obtained by Dr. Dahl and kindly lent by 

 Dr. f'ollett, convinces me that this little Kani,faroo should have a special jri'uus 

 formed for its reception. 



It may be described as follows : — 



General characters as in Pctrogalc, but the molars increased in number, 

 seven at least on each side and probably more, falling ont in front and renewed 

 behind as in the Manatee {Trirhechuf:). 



Sknll as described in the Cataloijue (l-C). 



The above remarkable characteristic of the molar dentition, only found 

 elsewhere in the Manatee,! is not easily seen on any single specimen, and has 

 not therefore been previously recognised. A normal adult Kangaroo, whether 

 Petrogale or other genus, has four molars, J increasing in size backwards, with a 

 narrow jj* in front of them, the latter having replaced a small similarl\'-sha]ied 

 ]? and a square mjA at the tooth-change. Bnt in the type of P. concinna, which 

 now proves to be quite normal, the most anterior tooth is molariform, and is 

 succeeded by four other similarly-shai)ed teeth, with indications of where a fifth 

 might have been later developed. This scjuare anterior tooth, about which I 

 expressed no opinion in the Catalogue, was definitely accepted by Dr. Collett § 

 as "ju''." But now the true y/, as in other genera, proves to be a narrow cutting tooth, 

 which is shed soon after eruption, and is tlierefore seldom found in jiosition, the 

 only case among the nine sknlls before me being in sknll No. Klls of the 

 Christiania Museum, where it was taken for j? liy Dr. Collett. || The young 

 examples of the present collection prove this determination clearly, for below the 

 normal narrow ;/" and square ni]i* an equally narrow ^/' can be extracted from 

 the jaw. 



Then, to solve the problem as to what the square front tooth of the type 

 really is, a careful comparison of the sizes of the teeth, carried out on the same 



' See Cat. Man. Jl. .V. p. 71. 18S8. 



t See Thomas & Lydekker, P. X. S. 1897. p. 595. See also Hartlaub, Z„ol. Jahrh. i. p. 1, ISXfi. 

 J For the sake of clearness the numeration of the teeth, both moLars and premoLirs, is here described 

 as in the Catalogue and in Dr. CoUett's paper— i.e., as though the following were the formvd.i — 



but later rcsearclies (I'f. I-yilekker, P. /.. ti. 18911. p. 922) indicate that tlie formula should rather be— 



, - 2. 3. 4 

 P.- M 



1. -L 3. 4 



"- 3- *• '■'■'ll. 2. 3. 



4. 



3. 



Later again (TV. Linn. Sic. 19(14), Mr. Bensley does not .icocpt tlie latter interpretation, so tliat the 

 provisional retention of the catalogue formula is the more advisable. 



§ P. Z. S. 1897. p, :i2G. 



II This tootli is 50 mm. in length, P' being only about I'l. 



