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96 On the markings of the Carapaz of Crabs. 
towards the eyes. These depressions divide the carapax into a 
medial region, two antero-lateral regions, and a posterior region. 
From the ‘medial, we exclude a frontal portion as a frontal region, 
besides also an orbital and from the posterior two postero-lateral 
regions. ach region has its several subdivisions or areolets. 
n the figure referred to, the areolets of the frontal region are 
marked F ; “of the orbital, O ; those of the medial, M ; those of the a 
posterior, P; those of the antero-lateral, L; and those of the BY 
postero-lateral, R;—R. being the initial of the last syllable in | 
the word lateral, while L is the initial of the first. The minor : 
subdivisions correspond to prominences or tubercles of the surface 
and are normally as follows :— : 
Frontal Region.—1F, the front margin; 2F a prominence | 
just posterior to the front either side of the middle. 
Medial Region.—1M, two small anterior prominences, the pr@- 
edial; 2M, two large areolets the extra-medial; 3M, a cen- - 
tral areolet, elongated anteriorly between the areolets 2M, the 
intra- medial ; 4M, a transverse areolet just posterior to 3M, the 
post-medial. Two deep punctures usually mark the limit between 
3M and 4M, even when there is no depression. 1M is annexed 
to the medial rather than the frontal region, because it more com- 
monly a with the former, and is a part of it often in 
general o1 
Antero- el Region.—In this region —_ are normally six 
areolets and they are often prominent :—1L, near the Jirst tooth 
following the post-orbital. 2L, 3L, eaicdes to IL, in a line 
nearly with the second tooth, and 4L, 5L, 6L, between 4M and 
the third tooth. 
Postero-laieral Region.—This region on either side consists 
normally of 3 areolets 1R, 2R, 3R. . 
Posterior Region. —1P is situated directly behind 4M and is © 
often well circumscribed, and sometimes in shape nearly like 3M 
reversed titi shortened. 2P directly behind 1P, is sometimes 
{ 
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Pent 
The variations in the markings of Crabs arise in the main from — 
the greater or less prominence of these areolets, their various sub- 
divisions, or their obsolescence. When only a few undulations 
but just apparent ; and when once perceived a correct sketch is 
made without difficulty. , 
n the obsolescence of the areolets, the posterior are the first to 
disappear, in which case this part of the surface is flat. Ne : 
postero-lateral fail of being distinct. Next 5L and 6 OL e 
