278 DR. H. W. MARETT TIMS ON 
The only evidence of the existence of prelacteal vestiges that 
I have as yet been able to meet with, is to be found in a paper by 
Adloff [1]. He describes and figures such vestiges in connection 
with Jd.3 and 7d.2 in Spermophilus| citillus (head-length 1-5 cm.), 
and Pd.2 and Pd.3 and 7.2, Pd.2, and Pd.3 in Spermophilus lepto- 
dactylus (head-length 2°71 cm.); also in Sciwrus Brooket in 
connection with Pd.2 and Pd. 3, though he does not mention their 
existence in two other species which he examined, viz., Securus 
Prevosti and 8. vulgaris. He further notes their presence in 
connection with Pd.3 and .2, m.2 in Cavia cobaya (1°5 em.). 
Thus there seems, at first sight, abundant evidence in favour of 
the existence of the Pre-milk dentition in these animals; but 
before implicitly accepting these statements, it is necessary to 
examine them somewhat more critically. Firstly, Adloff’s inter- 
pretation in connection with the molars of Cavza depends entirely 
upon his belief that the molars belong to the Deciduous or 
Milk dentition. In this opinion he follows Hoffman, Beauregard, 
Owen, Leche, and others ; on the other hand, Woodward, Lataste, 
and Magitot believe the molars to belong to the successional series, 
and in this opinion I concur. Consequently, according to the 
latter view the vestiges mentioned by Adloff in this position 
would be regarded as vestiges of the milk predecessors of the 
molar teeth ; and, indeed, I have already described the existence 
of such a vestige on the labial side of the molar teeth in a foetal 
pup of about the seventh week [22], as well as the presence of a 
“concentric body ” to the labial side of the molars in the guinea- 
pig; in both of which cases I have interpreted them as vestiges 
of a milk dentition, the lingual downgrowth representing a Post- 
permanent dentition. 
With regard to the existence of prelacteal vestiges in the 
premolar region in the afore-mentioned forms, I may point out 
that I believe them to be the only examples recorded, Leche’s 
and Woodward’s discoveries being confined to the outer incisor 
region ; the very region in which I found well-marked evidences 
of three dentitions in the dog, but in that instance the three 
undoubtedly being the Milk, Permanent, and Post-permanent. 
With regard to the presence of Pre-milk vestiges in connection 
with Pd.2 of Sciwrus Brookei, there are certain points to be 
borne in mind. 
As I understand Adloff, this tooth Pd.2 is the anterior of the 
two premolars so generally present in the Sciuride. He only 
