2 LS 
MR. W. K. PARK FIR ON THE STRUCTURE AND 
On the skull of the Centetidse. 
My materials for working out the structure and development of the skull in this 
peculiarly Mascarene Family of the Insectivora are as follows :— 
A. Stage 1.—An embryo of the largest kind— Centetes ecaudatus —7 lines long, 
(head 3, body 4), (Plate 16, fig. 13); this is intermediate between my 1st and 
2nd Stages of the Mole (Plate 1, figs. 1, 2, 3). 
Stage 2. — A three-fourths ripe embryo of Centetes ecaudatus, lyy inch long. 
Stage 3.—Young individuals of Centetes ecaudatus, 3y inches long. 
B. Almost adult specimens of Hemicentetes madagascariensis and H. nigrescens. 
C. An adult Ericulus nigrescens. 
D. An adult (or nearly) Microgale longicauclata. 
Stage 1 (Plate 16, fig. 13). 
In the smallest embryo the snout is just beginning to project from the front of the 
face; the brain vesicles (CP, C 2 ., C 3 .) are very large ; the eye-ball is very small, and 
surrounded by a circular lid ; the concha auris has commenced its folds ; the limbs are 
mere flaps ; and the tail is, relatively, longer than in the more advanced specimens ; 
the head is very large, relatively. 
Stage 2.— Embryo of Tenrec, Centetes ecaudatus, lyy inch long (Plate 16, fig. 14). 
The head is still ( and always will be) very large in proportion to the body; the 
tail is a mere stump, the limbs are well-formed. The eyes, and their lids, are very 
small, and so are the outer ears ; the snout is now a considerable structure, running 
in front of the lips. 
The skull (Plate 32) has acquired a large amount of solidity from ossification, both 
external and internal ; the whole structure is very evenly conical, with the snout 
as its obtuse apex. 
The investing bones. 
Seen from above (Plate 32, fig. 1) the endocranium only comes into view at the two 
ends ; behind, it is largely ossified. The scale-like superficial bones of the roof, the 
nasals, frontals, and parietals ( n ., f, p.), show their radiating lines of growth ; as 
to size, the nasals are broader, the frontals much longer, and the parietals much 
shorter than in the Mole and Shrew; they are more normal in this type. A large 
fontanelle (/<?.) still exists above, it spreads into sharp wings, right and left, in the 
coronal region, and in the lambdoidal to a less degree, where it runs back as a large 
semicircular notch in the huge, roughly crescentic interparietal ( i.p.). Here this super¬ 
ficial cranial element that is absent from all the Edentata except Orycteropus, but 
constant in the Insectivora, as in the Marsupials beneath them, attains its highest 
