614 PROFESSOR E. RAY LANKESTER. 
ceeds the thirteenth segment, as indicated by the superficial 
sclerites. 
Very marked differences, however, exist between the two 
animals in regard to the number of the glandular ceca. 
Whilst Limulus has but two pairs of ducts opening at an 
interval into the mid-gut (mesenteron), the Scorpion has 
(according to Newport) six. The first pair are connected 
with a peculiar pair of glands recognised by Newport, Dufour 
and Huxley (loc. cit.) as salivary glands. The opening of 
these ducts is placed at a point where the alimentary canal 
is slightly dilated, ‘The following five pairs of ducts are the 
conduits of a huge glandular mass, which corresponds unde- 
niably to the great saffron-coloured gland of Limulus. But 
in Limulus the relative enlargement of the cephalothorax 
results in the packing of the gland into that region, whereas 
in Scorpio the relative enlargement of the anterior part of the 
abdomen (segments VII to x11I inclusive) results in the pack- 
ing of the gland more posteriorly. The same difference of 
external proportions in the two animals results in a similar 
contrast in the position occupied by their generative glands ; 
in Limulus they ramify anteriorly to the genital orifice, in 
Scorpio posteriorly to it. - 
According to Newport, the glandular mass (which I shall 
call the hepatic gland, in accordance with custom, and not as 
implying that it is the morphological equivalent of the ver- 
tebrate liver rather than of any other outgrowth of the 
mesenteron) is divided into lobes or lappets, corresponding 
to the separate ducts. Dufour also admits this to be the 
case for the large oriental species of Buthus, but describes 
the organ as continuous, and with only four pairs of ducts 
(in place of five) in S. occttanus. The minute structure of 
this gland has not been investigated in any Scorpion nor 
yet in Limulus. By earlier writers it was spoken of in 
Scorpion as ‘‘ the fat body.” 
The Scorpions appear, then, to vary in the number of pairs 
of ducts possessed by the hepatic gland, and the fact that 
Limulus has but two pairs is, accordingly, not an important 
point of divergence. The absence of salivary glands is a 
more serious departure from the arrangements prevailing in 
the Scorpions. It is, however, to be remarked that on com- 
paring allied aquatic and terrestial forms of animals, salivary 
glands are not unfrequently found to be present in the latter 
whilst absent from the former. 
When we come to compare the proctodeum of the 
two animals we find, perhaps, the most important dif- 
ference which can be pointed to as obtaining between 
