Mr. J. Wood-Mason on Scolopendrella. 59 
their bases (where they are attached to two sinall oval sclerites 
nearly touching one another in the middle line), but above 
all in the important circumstance that they are never brought 
to the ground, but, on the contrary, are turned forwards under 
the head so as to be quite invisible from above in the living 
animal ; commonly, indeed, they are folded akimbo across the 
under surface of the back of the head; they without doubt 
belong to the head, and they must, as they follow the four- 
lobed plate, be held to correspond to the similarly pediform 
and attached appendages of Chilognatha, and, as a conse- 
quence, to the labium of the Insecta. 
The Somites of the Body und their Appendages.—The body 
of this little animal is extremely soft and fragile and exten- 
sible, and tapers visibly from the fourth leg-bearing somite 
towards the head, which is but little broader than the tergum 
of its hindermost somite. It is little, if at all, broader than 
high ; and the soft membrane intervening on its sides between 
the leg-bases and the projecting lateral margins of the tergites 
is complexly puckered and folded in a manner reminding one 
of the Chilopoda. It is defended above by thirteen (exclusive 
of the caudal somite, which would appear to be double) imbri- 
cated plates or terga, whose hinder margin is divided by a 
pronounced emargination into two rounded lobes. In this 
series of terga no such regular alternation of longs and shorts 
as obtains in many Chilopoda is to be observed, nor equality, 
nor regular decrement or increment, but, on the contrary, a 
marked irregularity in length—an irregularity, however, which 
is identically the same in all the specimens hitherto examined. 
On turning to the ventral surface, a consecutive series of 
eleven precisely similar regions, to each of which two distinct 
pairs of appendages are movably articulated, can readily be 
made out, or two less than the number of the terga opposed 
to them ; consequently two of these must be without either 
appendages or sterna, or two of the somites must be considered 
to be provided with double terga. In each of these sternal 
regions two pairs of sclerites are discernible :—a posterior pair 
of nearly circular and smaller ones, which, without doubt, 
corresponds to the small and similarly shaped ones that carry 
the hindermost pair of cephalic appendages, and external to 
which a pair of stout five-jointed and biunguiculate legs are 
attached ; and an anterior pair of elongated and larger sclerites, 
near to the postero-lateral margins of which, and between 
which and the legs, are articulated a pair of short setose styles. 
This arrangement of the parts at once suggested the sus- 
picion that each of the regions was made up of two sterna, 
each marked by a pair of appendages, the anterior and inner 
of which had become reduced to styliform rudiments—a sus- 
